I suspect that might change in the near future if telepresence with large, 4K screens showing life-sized, full body representations of people became commonplace. It seems like a lot of the necessity of in-person conferences and meetings is still things like realistic eye contact and subtle body language cues.
No, lower profit margins will kill it. With current enterprise software pricing you can afford lots of flights as part of the sales process. With SAAS type models you can't.
There will always be software that is worth the equivalent of millions of dollars (at least for the foreseeable future).
Maybe you can build a SAAS equivalent to SAP that puts it out of business... but companies will want a HumanBrainSimulatron (R) or a perfect weather forecaster or whatever the next complex software is, which will still be multimillion dollars' worth.
