Well, aside the fact Ash’s team sixth slot constantly free for no good reason?
I'd think latias' chance of capture are 50/50, but, it can just be a huge tease for nothing and they just want to recycle meloetta's plot with even less time.
I'm about 80 percent sure that he'll be getting Latias, since this mini-arc is all about Ash, and the suppose purpose of this mini-adventure, according to Delia Ketchum, is Ash wanting to meet and befriend new Pokemon while meeting familiar companions along the way. Meloetta was only an exception, given it was soley featured to promote its own story arc.
The Latias shown to us in this mini-arc, will not be getting its own micro-plot adventure like Meoletta, and is seemingly being used to progress one of the plots of the mini-arc adventure of Ash wanting to achieve his goal to befriend a new Pokemon, thus I'm guessing is the reason the writers are showing us why Ash currently prefers to carry just a team of five pokemon with him, leaving a vacant slot. It seems Ash intends to catch something, but cant seem to make up his mind on what it maybe, and I'm using the Clauncher episode as the primary running gag of this, and the fact of Ash questioning of seeing Latias again.
Its just way too many subtle hints for why a Latias capture should not happen. Latias just seems interested in Ash, and wants to know more about him for some reason, sort of a similar situation with Aipom. This seems to be such a troupe with a majority of the female Pokemon Ash catches; Chikorita, Dragonite, Goodra and Aipom. Ash does something heroic or shows his caring nature, and the girl mon's are instantly infatuated with this and want to smoother him as if Ash were Tenchi Muyo himself.
I hate for Ash to carry a team consisting of Bayleaf, Ambipom, Dragonite, Goodra and Latias all together.