I'd say that from as early as the 2nd lap of the race Kimi wasn't pushing in an attempt to get past Massa - it would've been utterly stupid to overheat his car staying close to Massa and risking an off in the turbulent airflow. Like kimi said they (both drivers) could've gone much faster.
It wasn't a race between the two ferrari drivers after the first few laps anymore... it was just waiting and making sure they switch positions before 75% of the race was run (if Hamilton was out of the top 5).
If it would've been the first race of the season rather than the last the Kimi vs. Massa "battle" would've been completely different. Kimi had the strategy advantage this time starting on heavier fuel and setting the fastest lap so would've been in a better position but it's impossible to know who was actually capable of taking the win in a straight out fight between the two.
Massa helped Kimi late in the season by often having enough pace to finish in 2nd, and especially in Brazil where a poor Massa performance would've meant no chance for Kimi in the title chase, in China he let Kimi down by not being capable of beating Alonso but that didn't matter in the end.
If Alonso would've been in 3rd and Hamilton in 6th with 1 lap to go Mclaren would've asked Alonso to drop back to 6th and have Hamilton in 5th to clinch the title, not doing so would've been stupid, although I somehow doubt Alonso would've done it.
