I would like a 4 card set up but I would have to change a lot more than just the case.
I would probably need a custom wc unit for the CPU to deal with the extra heat in the case.
A new bigger PSU with enough power leads.
I don't know if I could get away with the stock coolers on the cards or would they need wc as well.
It would be easier to start from scratch.
Still theres always next year
The new Corsair 900D looks very nice
If big Kepler ever puts in an appearance
And if IB-E turns out to be any good
Something to dream about