Sure the F18 can do the recon job, and very soon it will replace the prowler as EW aircraft too.
Overall cost when you reduce the number of plane types will prolly be alot lower from the days of having hornet, tomcats, corsairs, prowlers and intruders on the deck at the same time to having the f18 do all these jobs.
In the not to distant future the JSF, helos and hawkeye variants + the F18E will be the last of the manned planes on cv's. When the JSF takes over completly then the ranges and payloads of carrier planes will go down even more than they will when you now go from F14's to F18's