I don't need to check my math. If you want to finish Persona 5 in a little over 100 hours, then have fun speedrunning the main story. Never said you can't 'finish' 4 games before the end of the year, but I'm not sure why you mention a backlog if you plan to just ignore it.
Seems like my point of buying a couple games now, and then being able to get a new game once more have released just went right over your head. But I guess you have the master plan.
How long to beat dot come survey averages the game at 111 hours for main story plus extras on a casual playthrough. About 165 for completionist. They seem to be a pretty accurate site based on my experience. So yeah, I have done the research.
I think the Switch is great for first party games, ports of last gen games, indies and AA games like the Crash Trilogy and Octopath Traveler.