It's interesting to see that he'll go back to playing Estoril.
Especially, as this means that in case he'd also play Monte Carlo and Barcelona (an obvious candidate for another 500 event) he'd have to play five weeks in a row.
As for the four mandatory 500 events, I think it's clear that he'll play Basel. Which will make it two with Acapulco. Playing Barcelona would mean five weeks in a row without pause. So maybe Washington and then Beijing or Tokyo? I mean, it's not like there are too many options left and I don't think he'll want to play Hamburg after Wimbledon.