F/A-18E Super Hornet is essentially new aircraft, it's superficially similar and name was given to get funding from Congress though
It has over two times the combat range of C/D and carries a lot more weapons and fuel. It has longer combat range than Tomcat! Hornet's slower, though, but full burn uses fuel.
The F/A-18C's range with a standard combat load of external stores, assuming it has to fly back to where it launched from, is about 275 nautical miles. The F/A-18D's varies depending on the type of mission; most missile-based stores like SEAD, ASuW, or standard CAP loadouts give 370nm round-trip range, close-support loadouts heavy on the bombs drop it to 250nm. The F/A-18E's stretched fuselage for expanded fuel storage and improved engines give it slightly better radius, which also varies heavily based on stores it's loaded with but hovers around 400nm (which is less than twice of the C/D). The F/A-18F's combat radius is about 370nm.
For comparison, the ranges of the Tomcat the F/A-18E is replacing: Standard intercept loadout for an F-14B gives it a round-trip range of about 475nm; escort loadout gives changes it to be about 525nm. The F-14D's range with standard interception loadout is 525nm; the range with an escort loadout is 700nm. As you can see, the F/A-18E doesn't reach as far as the F-14.
The A-6E's ranges, for comparison to F/A-18F that replaced it: Bomb-based loads give it 600nm round-trip range, missile-based like SEAD and ASuW or precision weapons tend to be about 700nm.
Much as we don't like to admit it, the Backfires are still out there. China is reportedly interested in buying some; so are India and Iran. It's also known that Egypt, Iran, Libya, and China have purchased Badgers (and have the missiles to arm them), which would have been the secondary targets of the Tomcat. In some cases the Hornet's range isn't even far enough to intercept a Badger before it launches missiles. Whatever the decisions regarding the Tomcat, whatever the reasons for retiring it, was taken out of service before the threat it was designed to defeat was.