You severely downplayed Shulk, Isa, Chrom, Matthew, and Adult Isaac while overrated Saki, Young Isaac, and Takamaru (especially the last one, he is no guarantee yet).
Just saying.
Hoo boy. Firstly, I put Takamaru in the
exact same position you did. First, and a "good chance".
Secondly, Sakurai picks the most iconic characters to represent a series. He picks the face of the series first and foremost. That is teenage Isaac, that is Saki. Saki is a
little more debatable, but the only reason he would put Matthew and Isa in at this point with both series being in such jeopardy of continuing is either if Camelot/Treasure requested it (which we have absolutely no evidence they would do), or Sakurai is aware of some future game with Matthew/Isa as the protagonist. Camelot is making a Mario Golf game now, GS4 is pretty clearly not in development atm, or AT MOST in very
very early stages, if at all. S&P has never been a very successful series critically, and Treasure isn't fond of doing sequels. It's likely over. At this point (and at this point last year, when Sakurai was likely compiling the roster) Isaac (teenage Isaac) and Saki were and are the faces of the series. If a GS/S&P character is to be included, it will almost assuredly be them. Sakurai isn't going to make adult Isaac Isaac's default. He just won't. Adult Isaac is a minor NPC. Teenage Isaac is a two-time protagonist of the two successful games in the series, and still the face, and basically the "Marth" of the series. Sakurai including the most recent appearance of characters is not a strict and rigid rule he adheres by, it's a coincidental occurrence, because either the character never changes appearances, or their last appearance was also a major appearance for them. The sooner you realize this the better.
Chrom has a decent chance, no better. It's not good, it's decent. If he didn't have competition from Roy (who I'm not going to get into, your views about him are frankly... misguided), he'd have a good chance. The competition for the new FE slot is pretty tight, and all Chrom really has going for him is his recentness. His opposition is a character twice planned for Smash before, and the second most popular character in a region where popularity usually dictates the majority of the roster, and where the series gained its popularity from, and where Sakurai will look when choosing a FE character.
Xenoblade isn't at the level of several series that didn't even get representation in Brawl. Yes, it's critically acclaimed, and a great game, but Shulk's popularity is limited, his game's audience is limited, and his competition (in other unrepresented series) is fairly strong as well. However, he does have a fair bit of popularity in some circles, and he is one of the more prominent unrepresented IPs, however no more so than many other unrepresented IPs. Decent is still better than average.
Really though, the fact that teenage Isaac isn't anywhere on your list, not even under mediocre chance, is really incredible. And not in the good way. Same as you thinking Travis and Aeron have the same chance as Isaac and Saki. New IPs do not just get added because they exist. The new (non-retro) IPs added so far (past 64) are Fire Emblem, Wario, and Pikmin. Do you think Pandora's Tower is even close to them? Xenoblade isn't even close to them. GS is just within reach of Pikmin (it probably won't be after Pikmin 3), but even then, it'll be lucky if we get more than like three new (non-retro, non-3rd party) IPs this time around, and one will definitely be Punch-Out.
Anyway, with expectations and predictions like this, prepare for the roster to be a disappointment for you.