I very much doubt that this signifies anything new coming to Animal Crossing New Horizons. I could be wrong of course, and I'd
welcome being wrong on this matter, but considering what they said before, I consider that ship as having sailed years ago now.
Nintendo being Nintendo, I could see them seeing the sales of Animal Crossing New Horizons and just thinking "We can profit from this." by just releasing a console tie-in. I don't think there necessarily has to be anything else going on.
Since they specifically said there'll be no more free updates I always wondered if we'd get a paid update or another DLC at some point, but that's almost definitely just wishful thinking.
Someone can correct me if I'm mistaken, but if memory serves, the "last free update" wording was just the wording of the English announcement, whereas the Japanese announcement didn't say anything about "free" and thus people understood it to mean that there would be no more updates at all.
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As for these new Switch Lites, I continue to not understand why people would want to spend money on a console where the JoyCons aren't removable, considering the drifting issues and how you'd have to send the whole console to Nintendo for repair if/when drift does develop. Granted, I'm a person who prefers playing the Switch docked and prefers playing video games on the television, whereas other people prefer handheld, but the Lite just seems like more of a hassle given the realities of the Nintendo Switch.
Seeing these new ones, my brain at first was just like "Didn't these exist already?". They're seemingly using preexisting colors that Switch Lites have already been using for a while, and they've used the leaf pattern before on other products like carrying cases, so that explains it. Cool for anyone who wants to grab one though.