Access Analog (https://accessanalog.com/) is already doing something similar, and their system is around 300-2500ms latency (https://accessanalog.com/support/#1534876416634-f660a710-8f4...). A company cannot reliably offer much better than this latency, unless they have servers in all their customer's cities.

To most DAW users, 300ms is unacceptable, so any service that processes audio on a server needs to make this caveat very clear in their documentation. The problem with such a business idea is that local computers run DAWs just fine, so very few people would seek remote audio processing.