There’s still about 10-15 years before The Most Worthless Skywalker Of All has his emo-storyline in TROS that was supposed to white wash him of killing fellow students but still doesn’t seem to know what the hell his problem is, so Luke’s got some serious time for cover.
The biggest thing I’d notice here, though, is this; Favreau and Filoni clearly believe in at least planning one step ahead, which would be immensely beneficial to Luke, since that was something Johnson clearly didn’t do for *anyone* in TLJ. They’re not laying out absolutely everything down in concrete, but they’re at least thinking about what could and should be set-up next.
As such... I feel Luke’ story is already marginally healthier for TM giving him a student to help train who probably won’t be killed by Darth Affluenza - meaning that Ben Solo likely isn’t Luke’s last (and unworthy) surviving apprentice, but Grogu instead, so Luke’s not a complete failure anymore. It’s entirely possible F&F might have some ideas for what types of stories Luke should be experiencing now, aside from getting set-up for a pretentious Man-Pain story.
But I also wouldn’t be surprised if this was a once-in-a-lifetime move they made, and that perhaps broaching Luke’s story is still something you walk on eggshells with around LFL.