One big factor that will sway people towards (or even away from) XF will be the amount of useful add-ons available that people require to run their forums efficiently especially if they are migrating from other software where they already have these add-ons.
I was wondering if XF plan (obviously not in the immediate future) to run community projects to get highly requested add-ons to be created by the community and monitored officially by XF staff?
I believe IPB do this and it appears to be very successful. This can at least help fill the gaps where popular addons are needed but require a lot of time for single devs to pursue themselves and would off course distract the XF staff too much from working on the forums, to do themselves. I can see this being especially useful for bridge addons (with different CMSs/blogs/chat/e-commerce) and maybe even a way to get a script produced to connect multiple XF communities.
These products would obviously be free for licensed customers and help the community collaborate together rather than set up to create an income.