I honestly don't think so. GTA 5 released just 2 months before an entire new generation of consoles launched and it still broke every sales record out there despite not having a PS4/XOne version of the game for over a year. Plus, the heavily rumored PS5 Pro will still be very new on the market by the time GTA 6 launches, if it's still planned for Holiday 2024, so there will still be some additional new hardware on the market. 

As long as the game is BC, which most likely will be the case as that's been a huge priority for Xbox, then pretty much everyone who buys the next-gen Xbox won't mind waiting for the next-gen update since it'll still be completely playable. No matter what, people will always make sure they have a way to play a new GTA.

GTA 6 will be delayed to Spring 26.

That neptunia game also releases next week if I am not mistaken.

May get an early push in their new generation with providing the best way to experience GTA6, more so if it's delayed. Both would be excellent launch titles for new hardware.

Getting PTSD flashbacks to the Halo Moa pringles. Those things were awful. 

Another spin off.... its odd theres like 4 mainline games, and then a ton of spin-offs for the series.

Also the 2nd game is like a reboot of the series, with the same characters.
And the first 3 games where remastered with the "rebirth" title.
Then the V following the game title, doesn't mean 5, it means (V)ictory.... so theres Victory I and II. (V + VII)

Anyways these games are usually "self-contained" and don't require any other games to be played before hand to get whats going on in them.
They are their own thing, and usually Action-combat based.

I don't get the rumors on Xbox next gen in 2026.

Weren't the spec leaks for the Playstation device a clear indication that it was a PS5 Pro model, rather than a PS6?

If so, launching a PS5 pro model in late 2024, months prior to Xbox 5 coming out would be weird?