You would be in a world of hurt in which you’d have to live alone.
That is to say, since you’ll be running a fork, you will not be running Discourse and, unless you have a team of programmers to keep your program in line with updates from core, you’ll never, ever, be able to integrate future changes in Discourse into your program. Also, since you won’t be running Discourse, you wont’ be able to get any help here.
Other than that, you’d be totally fine.