I think the nearest around the corner addition will be Schnorr sigs. Apparently it should be easier to add than segwit so no miners drama.
I've read that a bit and it's already used on Monero, but AFAIK transaction size is still bigger than normal bitcoin transaction size and verification time isn't much different. Can't see the community will agree for CT + bulletproof anytime soon.
I agree Schnorr will be next major improvement added to Bitcoin and there won't be any drama as people who might start it already have their own drama
Looks like difficult topic, gonna read it later