It's not actually big news, is what I would say. Square is prominent to us because we know how it's growing, but it doesn't represent some insane amount of volume and this is only Square Market. It doesn't really change anything to say "a high profile tech company wants PR related to Bitcoin and to simultaneously test out what accepting it could do to their business". Every tech company is considering this - somebody probably brings up such a move to me every single day - and many are doing it. This is AWESOME and I'm excited to see Stripe and Square getting involved in BTC in less than a week (way more excited about Stripe btw) but for the larger value of BTC, it's NBD.
Other factor: the price of BTC is still REALLY high (not that it couldn't 1000x) and assumes there's tremendous (billions of dollars) value in BTC long term. Square processes billions of dollars a year in value, but not on Market and it's not many billions and not much of that will go to BTC.