Facebook and Instagram bans Cryptocurrencies ads. I think they are nothing to cryptocurrencies. Facebook users are not great market. It is only few percent of ICO market. I think cryptocurrencies will not die because of them.
Yes you're right, beside there are many social medias that are used by ICOs that can help more the publications of their ads or their project and these are twitter and telegram, they are widely used by many and they really help a lot in promoting the project of an ICO. Facebook is a very little part of the promoting industry and I think it will not affect cryptocurrencies.