What I would do is have the limit three fairies again. (of course)
There would be MUCH more membership privileges including shopping with ingredients. There would be less Pixie Diamond shops.
There will also be a feature where you can give fairies without SpeedChat Plus actual tours. To get that privilege, you need to pass a knowledge test. You can earn badges and special items in that feature.
I'm a little disappointed about the fact that you can't view all the badges of the fairy and can only view a member's favorite badge. Maybe you can view all their badges.
I would also add more meadows, shops and houses. Like Queen Clarion's Chambers and a Winter Border area. I'll also add more sensational locations and special fairies that appear during select events. (not calendar events. more like special shopkeepers)
I have a few more ideas but these are more important! Finally, here are some talent ideas. Remember that talent poll? There will be another one. Here are the options as well as the mentors:
Frost-Periwinkle
Art-Bess
Music-Trill (remade in Pixie Hollow fairy form like Dulcie and Zephyr)
Baking-Dulcie
Of course, I would use all of your great ideas as well. In fact, I wish Pixie Hollow could reopen and these features would be added! I really want that to happen!