If you really deconstruct Skylanders, you can see that it borrows many elements from Toys for Bob's earlier releases. The PvP battle arenas and varied characters come straight from The Unholy War (and Paul Reiche's work on tabletop rpgs); the focus on whacky monsters, the magic spells, the tongue-in-cheek humour and floating levels all come from Pandemonium!; etc.
I would like to see TFB develop Unholy War 2. They could easily market it as a grittier, darker, version of Skylanders. They could even use the portal tech etc., have players as 'commanders of the war' placing figures on the battlefield, like stereotypical generals do with tabletops dioramas of the battlefield.