I disagree with Scribe about that being on the table. I think it's possible, but only in the sense that, like, it's also possible that Ishgard could invade the Thanalan; yes, people are in position to, but doing so would require a will that I just don't think is there. A big part of Garlean history is that Garlemald is where it is because they were bullied off into the ass-end of nowhere thanks to resource scrambles, but the fact that they're in the ass-end of nowhere means that they don't really have a lot of tactical value to anyone else. Sure, they've got ceruleum, but they're also the only nation that really wants ceruleum enough to go kill for it. Much more likely is that they'll start trading with it with more niche interested parties like the Skysteel Manufactory than, like, Bozja deciding 'let's take their magic-oil'.
That only really leaves the motivation of raw vengeance, and... honestly, that's just not really how war politics works. Sure, wars can be drawn out longer out of emotions like that, and we've definitely got in-setting examples of that, but actually getting into a war in the first place out of vengeance, that's just... not really a popular or smart move in the real world or XIV's. Certainly, none of the leaders we've met are the type to do that (especially since most of them are at least generally familiar with why the Dragonsong War sucked), and nothing we've really heard about unseen occupied lands suggests they are either. Hell, remember that Locus Amoenus is still calling itself Locus Amoenus; there's not even will to change their name back, why would there be will to mobilize a 'Kick 'Em While They're Down' war?
All of these thoughts that Garlemald could get attacked are actually falling more into the rhetoric that Solus Galvus and his faithful weaved to justify their imperialism in the first place; that everyone around Garlemald are just inherently bullies, that they had to swing first because the notion that someone else would take from them was inevitable. And not only do I not think that any in-universe country we're aware of is that cruel or vindictive, I also don't think that we're playing a game that would do that.
The exception is the Turalian warmonger, but like Silvermoon said, I think that's more just seeing land ripe to conquer in general rather than specifically wanting Garlemald. I also think we're gonna put a stop to that before he gets to even set any boats out to sea.