The only way I see the talk about Ash's old Pokemon ending is that either he goes back for them or he finds out that they are no longer living.
I never understood why the writers even let him catch Primeape in the first place. Butterfree doesn't matter because it probably has children to help raise and as far as Pigeot goes, I really don't want to see it ever again. This is why I never enjoyed Kanto. Releases is the worse kind of troll on this show. Glad that it doesn't happen anymore.
Yeah that's what i mean, the writers obviously planned to have Primeape go pretty quickly anyway, i just don't see the point in giving it to him in the first place if it wasn't going to stay for longer.
Well... the writers simply wanted Ash to catch more Pokémon, so they had to get empty spots on his team. That's why he released his Pokémon back in that time, they didn't know how to handle this very well.
But Ash also sent some back to Oaks, and the ones he did keep on hand he released pretty soon after, that 6th slot had Butterfree, then it went and Ash got Haunter, if you can count it, and he let it go too, then he got Primeape, and let it go too, and pretty much from then on, without the league, that slot just stayed open, none of those pokemon after Butterfree stayed for very long.
In the dub, they said something about ash coming back someday to take Primeape, but unfortunately there is no such hint in the original Japanese version (That is why I hate the dub).
And Pidgeot, well... I think he released it, so it isn't his Pokémon anymore.
We may see Charizard (sadly :/), Squirtle and Gliscor again, but Pidgeot, Lapras and Primeape... I don't think so.
Ah right i wasn't aware it wasn't in the Japanese version. Yeah i agree that Primeape and Lapras have gone, even though Lapras lived up to what it needed to be by helping Ash through the Orange Islands, it was vital to him during that part of the series. As for Pidgeot, Ash also promised to come back for it but didn't which is also pretty surprising i think.
And as for the older pokemon appearing, I'm actually happy to see them return, including the 3 you mentioned, as long as they don't get rrammed down our throats, then i think it would be great to see them.