I'm not sure if the rest of Europe will follow but I think this is only a British/Irish proposal at the moment.
The
Guild of Air Pilots & Air Navigators (GAPAN) has been campaigning for some time to raise and harmonise Transition Altitude in the London & Scottish FIRs:
Position paper on Transition Altitude Policy
I can't find anything on their website but I believe BALPA supports the proposal.
10,000', 14,000' and 18,000' options are discussed in this
CAA consultation paper which includes a Response Form at Appendix 4.
The consultation period began on 31 January and is due to close on 1 May.