Both desktop OSes are moving in the direction of the mobile ones (app stores, signed code, sandboxes, etc.). For the moment, there are escape hatches, but they

Both desktop OSes are moving in the direction of the mobile ones (app stores, signed code, sandboxes, etc.). For the moment, there are escape hatches, but they are already disfavored alternatives (no promotion, no access to some new APIs, etc.) and, given past behavior, I wouldn't count on the escape hatches remaining open forever.