That is probably part of the motivation - the inventory of original IP to frack-mine from comics is limited, and Marvel movies have not figured out the formula to *evolve* new IP beyond the derivative (besides "hire James Gunn for a movie" which only worked for so long).
Deadpool is peak derivative / self referential humor - which is not a bad thing if excellently executed, but it needs fresh material and new foils. I'm very optimistic about deadpool vs batman on a marvel movie for the same reasons batman is excellent harley quinn's foil - it'd probably be like deadpool2 and x-men.
I don't know what DC will do with this, though - they have not figured out the "derivative exploitation" part outside of parody yet, and on the parody side there isn't much original with this setup the harley brand doesn't cover already.