Thoughts
BSL are very compelling I think. You want to charge money while you're maintaining it, but you want to allow the community to hard-fork.
The problem is that hard-forks (a project maintained by a different team with an independent vision for development of the same codebase) <-> cracks (an exact copy with the requirement to pay removed) is a slippery slope—in legal terms, they're both derivative works or redistributions with modification. (And I'm not concerned about "cracks" on like piratebay. Pirating will always exist. The issue is that under an OSS "cracks" will end up on Github and in distribution package archives with names like yoursoftware-community-edition. You could ask nicely, but you risk coming across as less respectful than someone just maintaining proprietary software.)
The first thing that comes to mind is some sort of poison pill—if you fork you cannot re-merge future versions. Maybe there's a way to make this work, but you end up with something that is not open source software in any way. You end up punishing redistribution of modifications in all cases. (With the thought that the punishment will be worth it in one case and not another.) What you actually wanted to do was prevent it in one case and allow it in the other.
Forcing a two year delay is a surprisingly elegant way of ruining the practicality of redistributing unchanged sources without preventing a community hard fork in the event that your organization stops acting in the interest of the community.
Edit: Realized what I'm describing isn't Business source since Business source allows non-commercial use before X years but I'm imagining proprietary before X years.