according to aviation week, russia is debeloping next gen. of stealth bomber, the bomber resemble B-2,except it use 2 engine rather than 4.
chinese bomber,likely resemble refine version of RAF vulcan.
china aerospace factory ,to date still un able to process a large single pieces of composite material.
I thought the PAK DA was more of a Tu-160 development rather than an analogue to the B-2...?
Or are you talking about something else entirely...
I can't see why the PLAAF would go for a vulcan configuration when it's well known the flying wing is the most stealthy and capable bomber design there is at the moment... and problems in developing large composites will still exist if it was a massive delta as opposed to a flying wing.
The only real limitation to building a larger bomber will be the lack of experience in large planes and as you say, composites. Stealth, avionics, aerodynamics are all areas aerospace industries should have experience with. I'm not sure how great those problems with composites still are (I believe a chinese company recently bought a european composite firm?), but they should only lessen as companies like XAC develop larger transport aircraft like the Y-20 and build brand new H-6Ks. Even a PLAAF NGB with less composites wouldn't be a bad choice as a filler for the time being, while later variants can be improved with more composites to lighten the plane and extend range, payload etc.