Cyclone III to IV migration

Hello all,

I am starting a new project which includes the design of an FPGA board. I will be using a Cyclone III or IV in the F484 or F780 package for this project.

I'd like to know whether Altera has made any plans for easy migration from Cyclone III to Cyclone IV E family (for the F484 and F780 packages), or whether the two families are not at all compatible.

Secondly, I'd like to know if there is a possibility to mount a F484 device on a F780 footprint (assuming that no IOs are used on the outer rows/columns of balls of the F780).

Thank you in advance for your inputs and guidance.

Kind regards