What better time for Facebook to make a move like this !
They recently lifted their ban on cryptocurrencies ads ( ban which helped crash the market in the first place...) and now, coinciding with a possible market bottom, a take over would make perfect sense.
The Exchanges are basically money machines, with an ENORMOUS potential, because, let's be fair, almost nobody is investing in cryptos, apart from well-informed people and some super-rich crypto moguls.
Let's assume for a minute that the number of people investing in cryptos doubles, or triples, or goes time 10 (which is very likely still an underestimation), the profits on the Exchanges would explode.
So again, what better time to buy yourself an Exchange, at least if you have the funds lying around :-))