That would actually be really cool. I see Tashigi's and Zoro's rivalry as another take on Kuina's and Zoro's. Zoro taking on the role of Kuina while Tashigi takes on the role of Zoro.
Zoro never got the chance to overcome Kuina in life. Should Tashigi ever overcome Zoro, it would be fulfilling a sentiment Zoro never got to experience.
I know Oda is building Smoker and Tashigi up to become enemies of the WG as well as allies for the Strawhats, but I would like some final face off between G-5 and the Strawhats. One where they can clear the air, come to understand the other side as best they can, then agree to work together. Luffy even suggested he and Smoker should fight one day when they are both at their best.