Not bashing vB -- again, this isn't a vB bash thread. My thoughts on vBulletin have recently changed. After reading, feel free to share your thoughts.
First, It's indisputable: license owner sentiment has been declining for a while now. When they go away or slow down, so do developers.
Indicators on vBulletin.com and .org, plus vB's recent actions lead me to believe their stream of new customers is slowing down significantly, and not only that, but people aren't renewing their licenses.
First, they made the amount of a first-time order $250 (to make up for a drop in sales), up from $160. Second, notable staff has been churning... a lot. Third, they released a SaaS platform at $15/mo.
Right now, vB knows they can't win over the existing customers they burned, and they don't care for developers -- as developers have mostly been useless for vB5 -- so it was time for a change in strategy.
The SaaS platform was made to address all of the core problems. It increases the number of first-time orders while also increasing the frequency of orders from the same customer.
In various ways, they'll begin to put the SaaS platform in the spotlight and try to coax existing self-hosted customers into moving into the SaaS platform -- maybe by throttling vB 4.x development.
That said, vB is still, after all of the recent customer dissatisfaction and staff drama, the leader in the commercial forum market. I'd used to say vB will crash, but trends and their strategies show that won't happen.
In the long term vB is here to stay. Rather than grow or shrink, it will go sideways -- but it's not going to suddenly dissappear. As a closing statement, all of this is contingent on one thing:
Nobody else with clout will come into the SaaS market and serve customers better and/or undercut them. Maybe this certainty was baked into IB's recent legal settlement with a big competitor.