There's no guarantee that they can refund 100% of the existing users' funds while their company is now dependent on public acceptance. They might suffer Bittrex's fate that users lost confidence after a series of the bad decisions by the management.
It is difficult to build back customer confidence with the experience of FTX. Although the challenges are not the same with bittrex, SBF is still trying to make good of the scam but I think he is not getting that easy flow on that with the amount of customers that he has shut out of their funds.