I say keep things the way they are (for the time being anyway).
I, for one, am an advocate of the League Cup and I would love it if we won it someday. Sure it's not as prestigious as the FA Cup but it's still a decent test imo - you will meet the big teams along the way (okay, they might field an understrength team but most of the time, their reserves are still of a decent level). One thing I've noticed over the years is that once a team gets into the quarters, that's when, say the big teams, start to take the competition seriously. In any case, the League Cup certainly gives our youth/reserve players the chance to shine.
The means of qualifying for the CL/Europa League should remain the same. Actually, one thing I would like to get rid of is the runners-up of the FA Cup being able to qualify for Europe if the winner already has CL football guaranteed and all that.....