Since Shimano is already the best performing Group set, in terms of shifting performance, I don’t see huge steps being made there.
The FD will likely improve a little, which is always good. Another cog is always nice.
However, things that would really be awesome in terms of improving actual performance:
more accurate power reading
increases shifting speed
finally a 12s chain, that doesn’t have increased friction over 11s
Significant weight drop just seems a little unlikely and I don’t really care.
PM being powered by the same battery as groupset would also be surprising.
Spider based Power meters are the standard today and probably the most accurate.
How would it be powered from the bike battery? It has to be turning freely, so it can’t really be cabled - not an expert on electronics, but I think that would be really complicated to do.
Also, you would likely need a lot of redundant technology, that would just weigh the bike down if no Spider based PM or another brand PM is used.
Lastly, why would this really be a big thing? I change my PM battery in Quarq every 6 months, and probably could go even longer. That’s really the minimum Service anything can require.
In my mind Shimano’s advantage isn’t shifting performance, I’ve tried all three (Shimano, SRAM and Campy) and the shifting is all fine. We could philosophize over the feel of shifts, whether they are softer, perhaps a tad slower or feel more like a bolt action rifle. But they all work.
Shimano’s big advantage is IMHO manufacturing. I don’t have long-term experience with SRAM yet, but I have a 9-year old XT groupset on my mountain bike, which still works much better than it has any right to. I’ve never serviced the XT hubs despite probably >20,000 km. That’s why I think Shimano is where it is today.
To be honest, apart from increased power meter accuracy I find none of these particularly important.
IMHO what would be more important is modularity to adapt to different use cases and as a result also wider range cassettes. We have new types of drop bar bikes that venture where only mountain bikes used to go.
The lack of modularity and flexibility is Shimano’s biggest weakness and SRAM’s biggest strength. (Campy should also be included sort of, Erkar is a great groupset from all I hear and even though Campagnolo markets it as a gravel groupset. They will also sell you a 44-tooth chain ring, and in no universe is 44:9 = 4.89 > 53:11 gravel gearing. I think Erkar is perfect for 1x road setups, too.) SRAM’s modular system covers everything (and is officially supported) from mullet setups to aero road road bikes. 1x or 2x? The rider gets to choose (as far as I can tell the gravel community is split in half here, and my new road bike has 1x gearing, too).
All get 12 speeds, you have cassette options from 10-26 to 10-52, quality first-party power meters for all offerings, and your only limit as far as chain ring sizes goes comes likely from your frame and not your groupset.
Shimano is missing the boat here, I think. Yes, it has its GRX line-up, but that seems to be a dam erected by internal company politics. Will the GRX Di2 levers (whose shape some people prefer) work with 12-speed Di2? Will 11-speed XTR Di2 work with the new 12-speed Di2 levers? When will 12-speed GRX components be released?
PS If 12-speed Ultegra Di2 is released at the same time, I’d want a(n accurate) first-party power meter.
The dura ace logo on this screenshot seems to be different to the logo they use atm…
In the meantime I found out that SRAM changed from monoblock to two piece design in 2019 because of whatever problems they had - will be exciting to see how the new DA calipers perform…
Disclaimer that I have absolutely no knowledge of how these OEM deals are typically structured. I did do this for my recent build (Ultegra shifters, 105 brakes, GRX derailleurs). While I have no issue, would or could Shimano try and discourage this to preserve the image that they’re distinct groups?
They can try and discourage it privately, I suppose, but product managers submit their spec to their respective factories, not Shimano, so when Shimano becomes aware of it, it is probably too late.
But if the PM’s are talking to Shimano beforehand and saying “hey, I’m kinda thinking about this spec…what do you think?” (which definitely happens), then again, Shimano could try and persuade them not to do it.
Moving DA and Ultegra to 12 spd and not GRX is definitely a bit odd now that I think about it. The industry growth at the higher end is in gravel, not road, so it seems a bit odd that they would not have a GRX move planned.
And it is really in something like gravel where adding a 12 cog could be sweet, especially if the rear derailleur gear range is increased. Imagine being able to run a 50x34 with a 11 - 38 or an 11-40. That would be a sweet gravel setup.
Very unlikely there will be 2x12 gravel set up anytime soon.
The current SRAM XPLR is probably your best bet, and I have seen people who have gotten SRAM 46/33 10-44 to work.
Shimano will release DA/ Ultegra 12s tomorrow at Eurobike, 6pm (CEST). There are several live streams teased already, also by magazines and shops. Availability is still the big unknown variable.
Will 11-speed XTR Di2 work with the new 12-speed Di2 levers? 
