I agree that the schedule change is not a concern : in last years (not only last year) Miami and Monte-Carlo hardly provided any points (and Doha is a small tournament which was not even countable last year), and he can replace a Basel final by a Paris semifinal which is not harder to do imo.
But his ranking can of course decrease because he had a great beginning of the year last year and it's unlikely that he will do the same again.
But yes rather likely losing his ranking to Murray than to Nadal in the short term, and it's not that a bad opportunity for Federer to be seeded 3, esp. on clay, if Nadal manages to keep his number 4-ranking in the first part of the year (which is far from done).
Hadn't thought of that yet. Totally agree. If this were to happen and Roger got murray in his half he could reach some clay tournaments finals more easily.
Well, Murray has 1880 points to defend prior to the clay season and Fed 2765 points. He's 2265 points ahead currently. If Murray passes him it will be because he plays well, not because Fed skips two tournaments.
I agree that a #3 seed with Nadal #4 is not without it's advantages, though a Fed - Murray projected SF in RG could happen regardless of who's #2 and #3. As for drawing Djokovic instead of Nadal, the advantage might not be relevant anymore - either will be very difficult to beat on clay.
Indeed, these are interesting projections for next year.