It depends.
Some attack missions will occur in contested environments. Just consider Kashmir: it's heavily concentrated with assets on both sides, and in that case, the JF-17 will be key. The PAF can fit the JF-17 with EW/ECM as well as a range of A2G munitions (anti-radiation missiles, LGB, PGB, REK/local-JDAM, etc). Some JF-17s can attack targets, others can escort the attackers. One platform, multiple roles, easy logistics/maintenance.
But the Mirages are more than just a strike asset, they're a strategic strike asset.
This is about having a 100 air platforms to join the 8-11+ submarines and 12+ frigates/corvettes, and dozens of land-based launchers of long-range cruise missiles to strike deep from any point. In this case, the upgrade path (if any) should work on firing longer-ranged, heavier cruise missiles.
Even in the US, China, and Russia, when a strike platform does well, you keep it and try flying it as long as possible, even when you have newer multi-role assets around.