It's an interesting concept because the Switch sold so well, and it lasted for about eight years. This means that there are a ton of Switch consoles in households, just like there were a lot of Wii consoles in households. In the olden days, the market would shift and look for something different, but we're not in the PS2 or 360 days anymore.
I think that customers are going to be more careful with their money, so they may be more inclined to stay with Nintendo and the Switch 2. This is where software makes the difference.
How did Sony pummel Nintendo, even when the PS1 looked inferior to the N64? Software. How did the PS2 outsell the competition? Software, marketing, and added capabilities (backwards compatibility and DVD player).
If Nintendo's truly interested in keeping customer's attention after one Switch, then they'll focus on software. They'll do a Nintendo Direct that gets people talking. Of course, a new Mario, Zelda, Smash Bros., etc. would be expected, but some surprise announcements would help boost the hype.
I think it's too early to say the Switch 2 will fail because we don't know what games are coming down the pipeline.