It is not only Google that is banning crypto ads.
Facebook is banning crypto aswell but we are talking about Ads.
Twitter goes with the same boat
http://fortune.com/2018/03/18/report-twitter-cryptocurrency-ads/But we could still Share, Retweet , Like etc...
Its all about the paid Ads those will be banned, I have seen many paid Scam Ads on my timeline.
So the good ICO's will get enough support on social media.
I dont think that it will lead to a big problem in th future.
Good thing they don't limit the use of their platforms, as long as we could tweet/re-tweet and share in those social media accounts i think it should be just fine while issue on google banning crypto ads i think that's a good move since fraudulent ICOs are being proliferated there.