Technically? Not too difficult. Strategically? They'd lose the Market (need to attract devs), lose Google apps (Maps in particular), and run the chance of dive

Technically? Not too difficult. Strategically? They'd lose the Market (need to attract devs), lose Google apps (Maps in particular), and run the chance of diverging from the Android API (making point #1 more difficult). Oh, and absolutely no chance of Google stepping up to defend them from patent suits (and for all we know, Google might target the rebels themselves).