Carbon or Titanium road bike, next/forever/last bike?

[AJS914]

@PhilSJones

Only catch is that around 5 years ago tyres and wider rims became popular and there are some wheels where I can only get a 23 on the rear, and one or two (Z404 for example) where I can get a 25 if the tyre is right.

This is the biggest knock against my 2012ish Colnago. It can fit a true to size and not too tall 25mm tire. It would be nice to bump up to 28 (probably an actual 30mm) sized tire.