Personally, I didn't care as much for TKxSF because I've always been a street fighter fan. I was happy that Capcom followed through with SFxTK. I love how much content it has and some of the unique features it has too.
I'm very please that Namco decided to include guest fighter (like Geese Howard too).
I think it's a better move for them to focus on their main series instead of creating a one off (TKxSF) that won't probably sell as good.
I would like to see more SF charactere as guest character for sure. I think Chun Li would fit nicely as a cop trying to take down tekken army, I would be very currious how they could implement a charge charactere like Guile too. I think they should keep Chun on here command moveset if they decide to make her join the crew.