There are already companies/altcoins that focus on this very thing, providing loans. Salt, Ethlend, Nexo and a recent find - celcius network. The average joe that comes to crypto and cannot trade will be lured in to "loan" out his crypto and get extra cash - the pitch will be, how would you like your crypto in your wallet to increase without you doing any work. With a return thats higher than what the banks will give you. Infact most of the scammers that call me, all try to sell me something that will beat just sitting on that money or anything the banks may offer in terms of savings.
As for margin trading - bitmex still continues to be the most liquid. Exchange is not the prettiest but it gets the work done in most cases - and even in that arena there are already new exchanges looking to steal a piece of that pie i.e primexbt and deribit. Binance will go far with margin trading but the fact that they are shutting down the US from most of the tokens trading and I presume margin trading too. Liquidity will just not be there as everyone else is on Mex.