Ditto on what broadwaydevil said in response to Playbilly. Really, if the Tonys move off of CBS and onto something else (PBS, Bravo, internet stream), basically the producers of shows would lose thier one National commercial. Granted, people bemoan the fact that the Tonys are not watched by the majority of American audiences anymore (no thanks to the fact that for the past few years, basketball finals usually occur on the same night), but I think there would be even less people tuning in if it was broadcasted any other way. So then why would producers pony up $100,000+ to present their show with a musical performance? Any musical numbers would probably be presented with just one or two performers, a mic, and a backing piano. And then we can completely forget about any play perfomances at all.
Bemoan all you want about how commercial the Tony Awards are, but this is my one time of year a majority of the country see what's going on in NYC.
Xanadu! Can't cry on cue!