Tell that to meloetta, buddy. Every rule have exceptions.
If latias is seen next episode, I'll believe.
You have a point with Meoletta, since many fans felt it would eventually become Ashs new pokemon, however the fact that Latias was introduced early on in the series and is now following Ash seems to imply that it will play a role in this mini-series. I think its obvious the writers are aware of how much fans like Latias, compared to Meoletta, so I dont see how it wouldn't end up being a part of Ash's team.
On the contrary to Meoletta, Krookodile did also follow Ash, with it appearing in random episodes, before Ash finally asked it to join his team. I think Krookodile, was one of or if not the only Pokemon Ash caught, that took him the longest to capture due to it constantly following him, before Ash realized it was meant to be his pokemon.
I just felt the writers teased us for a reason, by show casing Ash to only have 5 pokemon on hand in the first episode, after nursing Latias back to health, just for it to have second thoughts of departing from Ash, just to see it have an interest in him towards the end. If you ask me, thats a bit way too much of a coincidence for it to not amount to anything.