Considering the wii and 3DS eshops were kept alive several years into the switch's lifetime, how "soon" are you worried about?

This is a nice little update. I've had the game on my wishlist for a while and just saw it was on sale. Nice to learn that the sale is to promote the update.

I'd recommend starting with 4. It'll be the most feature rich and have the most quality of life features to make the game easier. Then if you like it you can go back and play the others. It seems like this will be the best of the series. (At least most highly rated)