How would you feel?
I don't feel like these games need frequent sequels. I'm completely bias because I don't have a Wii U so even a vanilla port would essentially act as fresh game experience for me, but I'm personally thinking back to the the 7 year gap between Smash Bros Melee and Brawl. Melee kept me very entertained for most of these years (even without DLC) and Brawl came at the perfect time. Both Smash and MK are 2014 titles, I don't think sequels should be a priority. Its not like they've aged poorly.
They're not campaign focused games so new characters, modes and levels/Cups should refresh the experience in a way that satisfies the majority of people.
Most importantly it frees up both teams to work on brand new IPs or visit other Nintendo franchises. Hal developed Pokemon Stadium 1/2 & Snap. Maybe they could help a AAA Pokemon RPG release in a timely fashion.