Voted 25/75. It's probably up to JP at this point as to when DT will pack it in. While Mangini certainly seems committed, we'll have to see how they all do with an album and tour. Plus, MM is 5 years older than JP/JM, so he could conceivably pull a Jon Lord and retire before JP wants to stop making music under the DT moniker. After all, drummers probably get physical problems earlier than guitarists and bassists, too. If it were someone younger like Wildoer, I'd probably vote 50/50 or higher, but the age factor is important.
Between Mangini's age, the fact that fans have yet to react as to how well the DT/MM music works (since we don't have an album), that they haven't had a tour to build/lose personal chemistry, and the fact that there's always the outside chance of an MP reunion, I'd put it at 35% or so.