I think IPB and VB have good reason to be scared, considering the flocking attention xenforo has gotten in such a very short period being live. I expect to see IPB and VB change to be more like xenforo as fast as possible, to keep hold of their customer base... but the problem with anything old, is that they simply won't have the underlying framework to compete that xenforo has, being so new.
The one discussion about the xenforo addon to run the addon section here already has so many possible uses, none of which is really in the marketplace by either VB or IPB, even though IPB have download addon, its not like what is coming here, which goes those few extra steps of being completely self supportive by each dev.
I can see the more importers done by XF and incorporated, the more will be converting over. Even Paul's VB4 converter... it brings over CMS, Blogs, Albums, everything, so you can hold the data in hidden forums until products are available... Xenforo would make me nervous being a competitor.
Love competition and the way it drives innovation. If XenForo can help IPB and vB become better products that in turn will only help XenForo become a better product. And who wins from all of this...the consumer.
1.1 looks like what I have been waiting for and even though XenForo right now works very well as a forum product. It feels a little empty without some of the features proposed for 1.1. Once that's released (and that wonderful Resources Manager), I can only imagine the jolt XenForo and this community will be given.
I give it 2 - 3 years of build and mod development time, and I would agree that XF and IPS would be the only two real commercial choices... but XF doesn't have the numbers just yet... growing, yes... there yet... no. I am certainly going to be giving XF a good boost along though.
That would be confusing because the author wouldn't be the same person as who recently replied to the thread. The relationship between avatar and username is solid anywhere else when they appear adjacent to each other like that.