Add Misty to that mix as well and we have dream cast reunited for one more ride.
Which would actually be pretty cool allowing for relationship to be taken to new level since they know themselves for long time, being intriguing to see grow of friendship and how would they interact nowadays. We could see Brock travel gathering knowledge from other famous doctors doing field research and having face ofs discovering new methods of treating, while Misty could go on quest to advance as trainer entering tournaments to become stronger trainer, collect various new pokemon and pass special tests to become E4 apprentice eventually. It would certainly bring her close to title of water master.
I always thought it would be good idea to reunite first cast for one more adventure. Maybe to prevent some crisis(whether because of pokemon or villains) along with tying up loose ends in their stories, and it would be nice way to wrap up long lasting show like pokemon ending it with those who started everything.
They definitely have potential to work again imo.
It would be an excellent idea to have the original trio reunited again for one last time. I always thought this group had the best interactions and plus they should tie some loose end on Misty's water master goal.