I doubt it. I'd imagine if one was in the works, we would have gotten that version instead of normal Generations.
Looking at past releases, that seems to be how they do it
4U is the only time we've only gotten the G version of an entry. I seriously don't get why people act like it's some traditional thing.
We got MH1, we didn't get MHG, we got Freedom which was a port of MHG.
We didn't get MH2. We got Freedom 2 and Freedom Unite.
We got Tri and 3U. Skipped Portable 3rd.
Which brings us to now, where we skipped MH4, got 4U and Generations.
We've missed a grand total of four games in the main series, and only 4U is an example of only getting the G version.
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The real reasons I'd say there's no reason to expect an expanded X/Gen would be that the entry is in itself unusual, as an extra entry in a generation, and that there's been no Japanese announcement even though it would probably be coming out in 3-4 months if it was a thing.
Edit: It is unusual that there's been no main series entry announced for Japan yet for this year, though. They've yet to go a year since the series began without a main series entry in some form.