I don't know. I guess nothing serious will happen in case YouTube and Instagram would be banned. Several hundreds of mostly very young people would be arrested here and there - protesters. Many people would find ways to still use Youtube and IG. Many people would find entertainment on rutube, vk.com, telegram.

Maybe I am wrong. Ultimately, nobody can predict.

I think poverty will make people upset. But we have an example of Belarus.

No idea what will happen :) Probably, a big collapse in 2 or 10 years or 50. ) Or maybe a new Khrushchev will appear. Or Gorbachev :) Who knows :)