That's really smart design right there.
I'm highly considering getting this and possibly using it in combination with a weekly regime (like 30 minutes of Ring Fit, 30 minutes real jogging, or other substitutions).
Still waiting for my job schedule to change to its permanent schedule so I have a better idea of planning out my time.
Did they say if they're going to update with new routines?
Sadly no word on updates yet, but the story mode for the game will likely last you well over half a year if you do it 4-5 times a week. There are a wide variety of exercises though, so I don't think you'll get tired of the variety there.
I do hope they announce DLC updates though, if any game is begging for it it's this one.