many things can be done with Saints Row.
- a SR game set in Stilwater -so same SR1/2 city- after the boss left to steelport, play as low rank 3rd street saints guy to be new boss. (this wont costs much since it'll be like an Expansion pack to SR2)
- Revive Saints Row: Drive-By the cancelled 3DS game.
- just ports, SR Stilwater collection (1/2 ports) or Steelport (3/4)
these options will not costs Deep Silver and Volition much and having the series on Vita where nothing similar to it available mean potential of good sales since there is no other alternative.
Someone HAVE to have an open world game planned for Vita, a port or spin off where most assets are already there should make up for the money spent on development and then some. A known franchise like SR should be able to make good sales even.
I hope Sony puts some more money into marketing the Vita together with the PS4 now.