The real truth of things would appear to be that Mats Sundin may indeed be leaning towards retirement. With all the press coverage on his situation the last word that I heard was that he still had not begun skating in August. For any NHLer, let alone a 37 year old, not hitting the ice going into the Labor Day weekend is surely considered as a bad sign. A player coming off an injury/surgery might get away with it, but not a guy looking to stay on top of his game. With this in mind, I'd expect that Thursday would be a reasonable indicator. If Mats hasn't started working out by then - and I'd be shocked if such news wasn't reported in every corner of the hockey world - then I'd expect odds to heavily favor Sundin skipping NHL training camps this fall.
We may have an answer that a lot of fans don't want to hear, but this week is certainly going to tell us a great deal about the big swede's upcoming season.
Sundin busted his ass off last season to get stronger, I think he realised that the NHL season is just too long for an older guy to continually push himself harder. If Mats comes back he will go the old fashioned way and just used training camp to prepare. He will have that much more at the end of the season for whichever team he chooses to play for.