The main threat is simply other exchanges. There are so many propping up every quarter trying to be the new binance, some offering little to no fees and incentives as well.
That's not a threat, but something I very much welcome. I would love to see exchanges as Binance and Coinbase shrink down significantly.
It's going to be an interesting time with how legacy banks will soon start to offer the exact same services as Coinbase, because the amount of money that can be made in fees is too interesting for them to discard. It will also increase the legitimacy of the trading desks themselves, and hopefully result in more liquidity with how people right now don't trust exchanges.
Say about banks what you will, but they are 100x more trustworthy than a silly crypto exchange, and they know how to handle insanely large amounts of money, which can't be said about crypto exchanges that are operated by a bunch of amateurs.