Are we even getting a mid-season patch this year?
It's too soon to know if and when they would it, the season is just 3 months old.
But even if the game would be super balanced, I'd bet we'll still get a mid season patch with several minor tweaks, changes and fixes. Characters always can be improved or made more accesible to people, and even if they are already ok there are people with different tastes so to make changes you can make them appealing to other people, or just to make the game feel more fresh, with new things to learn.
In the last month they announced like 3 or 4 new Street Fighter V eSport events with huge partners which means that at least Capcom is going to support the game for minimum one or two years more, and to do so they'll need to keep releasing new stuff like new paid DLC content to generate revenue (characters, stages, paid costumes, paid colors...) in addition to free and unlockable stuff (gameplay tweaks and fixes, new extra battle and fighting chance costumes, new characters, new game modes or features...) to keep the players happy and engaged playing the game for longer because you need to have people playing if you want them to buy the DLC.
In addition to this, seeing their first external partner for in-game ads seems a pretty good strategy for them to follow with future sponsors: they promote SF related merchandise that also generates Capcom licensing revenue (remember, Ono is also in charge of SF related business) with stuff that players like and doesn't feel that invasive because it's game related and provides some cool Street Fighter new artwork for loading screens and extra in-game money. Something similar to their cosplay costumes: they keep players engaged unlocking cool stuff that also helps to make their other old brands more popular and to promote recent games (MHW, RE2, DMCV, etc), while also helping to bring fans from these other series to SFV.
So I'll bet we'll get a mid-season patch and since this strategy seems to be working and sounds promising, I'd bet we'll also keep getting crossover costumes (we know from datamining that they seem to be coming) and more in-game ads of SF merchandising or SF related products (maybe comics, movies, small arcade cabinets, toys, figurines, clothes, etc).
So since Capcom will want to keep people playing the game and getting these things, they'll need to keep adding free stuff to keep fresh and alive, like the gameplay tweaks and changes, and at least until now it meant a mid-season patch.