Hi dpoverlord, welcome to our forum! Impressive setup you’re running there, at Club 3D we’re big fans of multi monitor gaming but of course we prefer an AMD Crossfire solution.
In reply to your question, no, hooking up an MST Hub to a console doesn´t give you enough GPU power to run your huge 6400x 2560 resolution. The current PS4 and XB1 pack just enough punch to deliver playable framerates in 1080p resolution, they are not designed to go beyond that. Keep in mind that those consoles can be compared to a mid range gaming card, somewhere between R7 260X and R9 270X. So even if you run a ‘light’ title and your console would feature a DP output, you won’t be able to power all those pixels you have there.
That’s why PC Gaming is miles ahead of any current (and upcoming) console!
Do I understand correctly that you were running a pair of Titans in SLI which both died? That would be a small disaster for your wallet!
If you are looking for an affordable replacement, consider a pair of Club 3D R9 290 royalAce cards in Crossfire. Two of those will cost you around half of one Titan (!!) and will offer roughly similar performance. They currently offer the highest performance ever at this price point.