As for your question, "how much will handheld PC gaming impact the Switch's successor?", the answer is, it depends on the point of view. Since you didn't mention what kind of an impact would that be, I could say at least two things. One is saleswise, and I guess the impact in sales would be minimum, even if people like myself might skip, for example, upgrading my OG Switch to an OLED model in case I'm able to put my hands on a Deck. It dents Nintendo in sales, albeit minimally. Another impact is techwise, and this is much more wishful thinking from myself than anything else, but if the capabilities of the Steam might serve as a parameter, Nintendo should at least consider it as a bare minimum output for what the Switch's successor should be able to run in 2 or 3 years from now. Otherwise I could really consider skipping their next system to wait for the next Deck, thus coming back to the sales dent from the earlier example. These are the main hypotheses of "impact" that I consider relevant, at least for now.
My 1000th post: https://gamrconnect.vgchartz.com/post.php?id=9368779
