In the long-term, Pakistan should team up with countries such as Ukraine to jointly develop & produce a fighter-use turbofan engine. As I said many times before, it would be a prudent decision to start ASAP and gradually develop over 15-20 years - so that we gain the experience and means, as well as end up with a mature design when necessary (for not only JF-17, but also other programs in the future). This is flexibility and indigenous support that we need...
In the short and medium-term, we'll have to rely on foreign systems - but we can localize certain aspects. For example, Pakistan can produce non-sensitive parts on license; be able to fully maintain and overhaul the engines domestically; and perhaps contract the firms in question to lend a hand in teaching and transferring technologies they deem non-sensitive - so that Pakistan at least has a start.
JF-17 itself will continue using the RD-93-series...even upgraded variants, such as the reported "RD-93M" which would include higher thrust, FADEC and maybe even TVC. That said, Pakistani officials stated very recently (Farnborough) that they have options beyond Russia and China, and my guess is that the SNECMA M-88-3 (90kn+ thrust). With the Rafale not breaking through into the market, I think the French would be quite happy to sell something off the Rafale...