I was just thinking how strange it was, given how much Naoko clearly loved him, that Mamoru/Tuxedo Mask never got his own side story, so I'd be into that. I also find it curious that Rei gets to celebrate her birthday (twice!) in the manga, Usagi and Chibiusa get to celebrate theirs, Mamoru's birthday gets mentioned, and Makoto and Minako celebrate their birthdays (together), but Ami never gets to celebrate hers, so a "Happy Birthday Ami" side story would be fun to see, too.
As far as I know, September 10th is (or was back then in the 90s) exactly the day when the new Semester/School Year starts. So bad luck for poor , she'll have to wait 'til after the lessons to celebrate.
It almost feels like Chibimoon and the Asteroid Senshi were specifically set up for a potential "next gen" series, so that might be something worth exploring.
Something I'd also be interested in seeing is a side story on Galaxia's conquest of the galaxy. I strongly suspect there are a lot more Anima-mates than just the ones we saw, and it would be interesting to see their dynamic fighting against "real" senshi and collecting their starseeds/Sailor Crystals, and bringing more warriors into the fold. There was actually an RPG along those lines years ago, and it looked really interesting.
On that note, the OVA about Ami in SuperS was pretty cool and had nice animation. Having three other OVA's in that vain for the inners would be sweet. Though its a couple decades too late to see that style the way I envision it
A story to flesh out the Starlights more would be nice. having them in just the last arc does not do these girls justice
Show us where the characters are now. Present a new villain and show Neo-Queen Serenity having to find strength to transform into a new form Sailor Moon one last time to defeat it.
The possibilities are endless, but it’s really up to Mrs. Takeuchi to decide what to do with her franchise—my opinion is that if she is not in the mood to create a new story, then let other creators full of passion do it. The moonlight carries the message of love.