On paper ZDK-03s may appear better platform than Erieyes, but in actuality Erieyes are more advance and reliable than ZDK-03s. Swift Retort has also stamped the Erieyes operational capabilities. There are certain limitations of ZDK-03 regarding communication (with non Chinese assets?) and information gathering (its more prone to EW, share less precise data?). Therefore, It's safe to assume that PAF will standardize its entire AEWCS fleet with Erieyes for covering all three primary sectors (North, Center, South).
If that happens in future, (theoretically speaking), ZDK-03s may be pushed to Navy (as part of Naval Aviation). Meaning, an improved ZDK-03 fleet could be employed specifically for Maritime operations. As Navy is increasing in size, it's also improving its physical presence farther South of its AORs. If there will be more warships and subs, then there will also be bigger and better naval aviation. Hence, ZDK-03s can find their role for enhanced coverage of Pakistan Maritime Domain.
They will be different from Sea Sultans as (1) they will primarily cover the aerial operations, (2) will serve as communication nodes for establishing network centricity, (3) will increase the envelop of Pakistan airborne area denial prowess, (4) and act as Airborne command & control systems for coverage of coastal, aerial, sea surface and submerged assets.
*Year ago, there was a proposal for customizing a pair of ZDK-03s with refuelling tanks. Meaning, ZDK-03s will be able to act as supplementary aerial refuelrs. It will be interesting to see in what capacity that proposal will materialize? (provided it has not been rejected already)