I agree with both Mosh and bosk. At this point I'd say it's a toss-up. Ultimately though I'm not too worried about it because both DT and MP are doing good things right now.
Although it is far from impossible, I would not remotely consider it a "toss up" either. The members of DT have stated that they are clearly not interested. Add to that the fact that there is no vacancy and not even the slightest indication that there is likely to be a vacancy in the foreseeable future. Unless and until there is at least some small indication that the parties involved are even remotely interested in it happening, the default is "it ain't gonna happen." Could that change? Yup. But as of right now, there is zero indication that anyone wants it to, and many indicators that they do not. It is not even close to being a "toss up" right now.
In my mind, I guess it's somewhat close to that because of all that could potentially happen over the next little while and because of the history between those guys. Nevertheless, I totally understand what you're saying and would actually put the odds at somewhat less than 50% (but not at something ridiculously low either).
I think it's kinda strange how people seem to think--based on absolutely NOTHING--that MP being back in DT is pretty much a done deal.
Also, I think (in Prog Snob's defense... maybe), that it's totally possible for someone to just have a sense about something and be pretty confident. Maybe he doesn't actually think it's a done deal, but he has a really strong feeling that MP will be back. He could be wrong, for sure, but... I could definitely imagine there being an Iron Maiden fan in 1997 being really really confident that Bruce would be back getting told by everyone else "it probably isn't going to happen," and coming out being right in the end. Doesn't mean it'll happen, but I guess some people just get a sense about something like this and can't easily be swayed on the subject... and sometimes they turn out to be right.