Yup, both di Resta and Perez have stated their interest in IndyCar. Actually a bunch of Euro ladder drivers have mentioned it.
Amongst di Resta and Perez, Antonio Felix de Costa, Narain Karthikeyan, Karun Chandhok, and Sam Bird have all expressed interest in moving over. Personally I think di Resta, Bird, and Perez would be fantastic additions and would greatly strengthen the indy field