Well, Ramsey will have the northern alliance, so it won't be a case of being cornered by two armies. Expect one of Jon or Lord Baelish to encounter Smalljon Umber or the other northern tribesmen before encountering Ramsey.
As for Tyrion, he's suffering from Dany disease - needing to find little things to amuse yourself with while the story happens elsewhere. This slavers mess will be cleaned up when Dany runs through with the Dothraki.
I am quite enjoying Cersei's maneuvering. As we know, it never ends well for her. By season's end she'll be childless and, perhaps, looking at a Tyrell ruler in her home.