As per Shimano, this will only be available for the TT shifters…
I don’t think that was ever in the cards, I think you had the wrong expectations here. Such a move was never in Shimano’s interest. They only do it for the TT shifters, because “redesigning them” for no reason would not be in Shimano’s interest. (I say for no reason, because the brake levers are separate and work just fine. And the shifter is electronic, doh!)
Thanks for your reply…
I’m aware of it having Sram red axs… I was thinking of switching the chain as well…
Probably we should wait and see if someone try it…
Thanks @mcalista As I have Shimano double (Bars & base bar) Di2 11 on my TT bike this is very interesting. Especially as the 11 speed wheels will take a new shimano 12 speed cassette.
I am curious how this then connects to the rest of the system given the new 12 speed sends a wireless messsage to the front and rear 12 speed mech.
Question - is it “merely” running an old style sd300 cable through teh frame to teh new 12 speed parts?
PS where did you get the diagram from? The shimano website for the EW-AD 305 mentioned earlier is not helpful.
Yea, this is the weird part for me. Di2 shifters are just buttons. Unless I’m wrong, I don’t see how the signal from a TT shifter would be different than a road shifter. So the fact that they can allow the older TT shifter to shift 12s with a software/firmware update would make me think they can do it with the road shifter. Just use the adaptor as in the diagram and update firmware.
9200 di2 can still be run fully wired if you want (improves the battery life).
The new cables are a smaller diameter, so needs the EW-AD305 to convert the old cables to the new connections.
I lifted the diagram off cyclingtips.com, but I have seen it on other sites, so I am assuming it was in the Shimano media package.
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One concern is the chain. My guess is 12 speed will be narrower than 11 speed. Not sure how or if that will affect the shifting on the FD.
I’m struggling with this too… I think it would take intentional effort by Shimano to make the old road shifters incompatible. We’ll find out soon enough 
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I dont think they are. Some mention (maybe on the @gpl video?) the cable connectors are different.
I think the battery might also be different (same size and shape, but connectors might be different)
From the video, I think you need a converter box from old TT shifters to new cables and a firmware update.
So the only thing you can probably reuse are the shifters.
Yes, technically that should be easily possible. But Shimano doesn’t do it intentionally, because they think they make more money this way.
Is not. There is only one reason for not allowing this: Shimano WANTS you to buy the new shifters. They want people to spend the extra $700. I mean, If you want to go wireless, sure. But let people who are happy with a cabled system keep it.
TT shifters apparently is such a low volume (compared to road) that they dont care as much.
You still need a firmware update of some kind… not sure why.
But as a software engineer who has work on hardware, there is 0 technical reason why they cant let you use current shifters, other than the stated want more money.
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I’m guess it would be the same way they knew when you were trying to use a 10 spd shifter with an 11 spd system and eventually blocked it out. I’m sure there is some kind of “identifier” signal in the shifters (or whatever the technical term may be…I’ll defer to the software experts here).
I recall reading on weightweenies that some people have been using XTR 12s chain on DA 11 with no issues
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Shifters aren’t simple switches because Shimano made them to not be simple switches. Original version 1 Di2, that’s exactly what they were. We used to make our own TT buttons and climbing buttons out of momentary switches. We would also take small batteries that cost $20 and replace the absurd shimano external stuff. But, you know, Shimano didn’t like us hacking away with $10 and $20 parts and soldering irons when they could charge $100s.
So with eTube they made the wiring harder to hack and added microchip encoding to each shifter. Note, you could still hack in momentary switches, but you needed to scavenge the microchip too instead of just splicing in.
Same reason they won’t let you program a derailleur for any cassette spacing - they don’t want to. Since there is basically a duopoly on bike parts its gonna stay that way. Good for Sram and Shimano, bad for consumer. Lets go tilt at that windmill 
Regardless, those new groups are very nice. I’d put that D/A set on a new bike in a heartbeat. Probably will in a couple years.
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What are you talking about!
Its all about the “safety of the end user” /s
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GASP…a company that wants to make money!!!
OK, snark aside, let’s be realistic. Shimano is a large company that is publicly traded….their goal is to make money. They just happen to do it selling bike (and fishing) stuff. They aren’t a bunch of bike geeks trying to make cool stuff out of the goodness of their hearts and giving stuff away at cost.
Sure, it would be nice if they allowed people to mix and match, but that just isn’t realistic.
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I am not arguing that.
They are entitle to do this.
Its their product and they do what they want.
It just sucks as a consumer, knowing a company could do something “nice” and “consumer friendly” and actively decided against it.
heck.
They could probably charge for an “firmware” upgrade.
Say, Charge $100 to get a the firmware to let you use 11 on 12 speed system
But at the end, most people buying will get the whole thing and it will be a moot point.
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You had better get your order in now then!
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The debate about a product being different than old products is RIVITING!
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LOL - I’m not in a rush but had the same thought. Will be interesting to see what types of premiums folks pay to get the newest stuff.