Alright, lets go with your example. You P2W you way to the best ships. You no longer need credits. So what do you do in SC next?
Explore the gala.... nope can't do it, just one Star System.
Fight for a faction to raise their influence in the System?
Fight for a local Warlord to take over some Settlements or Bases on the groud? Perhapes a Space Station in Space?
Engage in a Massive PvP conflict zone for the Player Orgazations control over a piece of land or Space Structure?
Discover rare species on the planets?
What is the end game for you, after your ship grind is over via click of your credit card?
Well, technically speaking, you still need to upgrade you ships. So there is a need to grind (or not grind) there to get the upgrades.
Except... CIG have said they will continue to sell UEC even after release... so, suppose you can just buy yourself the upgrades.
Technically speaking, the amount you can buy per month is meant to be limited, but easy to get around that, just use alt accounts or friend accounts and transfer the credits over.