I don't know what kind of addition and changes they are planning for 3.1, but here's a thing I think would help bring a lot of people to chocobo racing and keep it alive for a longer period of time: make it accessible via duty finder.

I think we've all been there waiting for gathering nodes to spawn etc., chocobo racing could be used as a filler when you don't know what to do or are waiting for something (that isn't a queue of course...). As it is now, you have to expressely be at the chocobo square, I think this is bad, because you might just want to do a couple races, and people can't be bothered to teleport to GS and then go to the chocobo square just for one or two races. Basically, I think accessibility would improve chocobo racing a lot, and more people would be open to give it a try.
Chocobo Square could still have its use as you still have all the chocobo stuff vendors there (breeding permits, skill manuals) and if you ever want to retire your chocobo you'd have to go there.