vmw
An alternative is the rumoured contemplation of Sony Creative Software to include a full DAW in Vegas Pro video. They already have the expertise and could provide a real threat to Sonar.
Okay, now I understand...you're a time traveler from 1998, and you missed all the stuff that happened between then and now.
Vegas was introduced in 1999 as a DAW intended to compete with Pro Tools. The only connection to video at that time was the inclusion of a primitive video preview window. I first saw an early rough version of Vegas during a private showing at Frankfurt Musikmesse, and told the person showing me the program that not being able to support control surfaces would hold them back. Aside from that, though, I thought it was more capable and straightforward than Pro Tools.
However the program didn't get traction against Pro Tools, and in 2000 Sonic Foundry released Vegas Video 1.0, which allowed putting multiple videos on a timeline in a variety of formats, and editing them. (FYI Final Cut Pro didn't have this capability until 2007.)
Vegas can already do ASIO, run DirectX and VST plug-ins, has buses, and other common DAW features
because it started life as a DAW. About the only thing left to add is MIDI. With Acid seemingly no longer being developed, perhaps Vegas will port over Acid's MIDI implementation but don't kid yourself - Vegas is about [great] video editing that was built on a DAW chassis, which it retains to this day. That's one reason why musicians find it so easy to get into video with Vegas.
I'd be willing to bet the odds of seeing serious notation inside Vegas are about the same as seeing extensive non-linear video editing within SONAR.