I think that Feyenoord will win the title this year. They have played very well since the beginning of the season and they deserve it.
But Ajax isn't far behind them and won't give up till they win the title.
9 matches left to reach end of the season everything could be happening and the main problem is could Feyenoord had win results in the rest of matches because if they slipped at least once time i'm pretty sure Ajax will more near to first positions because 4 difference points is not huge
For me it's a done deal for feyenoord because they have their own destiny in their hands and it couldn't be more easier than having 4 clear points ahead and with relatively easier games to play. Their only enemy could be complacency and they should guard against that.