MS should buy amd. They can use them for their devices division
MS could use AMD, I suppose. But AMD's interests aren't perfectly aligned with Microsoft's, so they might end up gutting the company.
That said, AMD dying is in no one's interest, except Intel and Nvidia. So in the event of really severe financial trouble, I think AMD could turn to a few big players for investments. OEMs certainly come to mind, as they really need competition in the CPU, chipset and graphics markets to get good prices. And here Rory Read's ties to Lenovo make the latter a good candidate, especially since it's recently become the world's largest OEM.
Microsoft would be a good candidate too, they've got a lot of money and need the PC space to remain healthy, could use AMD's mobile APUs in their Windows tablets, not to mention AMD hardware in the Xbox.
Samsung and IBM both make AMD machines (servers for IBM) and benefit from the silicon volume generated by AMD in GlobalFoundries, which is part of the IBM Alliance to which Samsung also belongs, so some money could come from them too.
But actually, apart from the recent contraction of the PC market, AMD is doing OK. Trinity is better than Llano, Vishera is an improvement on Bulldozer, and GCN is great. The HSA foundation has reached critical mass (almost all the big ARM guys, Apple excepted) and even their Gaming Evolved program is finally yielding results. Their software tools may still be somewhat immature, but they have their first really HPC-worthy architecture, with all the right features (easy-to-compile-for, scalable architecture, ECC in all internal and external memories, fast DP, etc.).
Their roadmap looks quite good too. Not "earth-shattering, oh my god Intel and Nvidia are doomed" good, but definitely "back to black" good. Steamroller looks good enough to significantly improve AMD's competitiveness and margins, Temash checks all the right boxes for the Windows tablet market, to the point that I'd almost want to buy one. And Papermaster's SOC approach with HSA is arguably the smartest way AMD could go for the booming mobile market.
But if the rumors are true, Kaveri is massively late and AMD's about to fire 30% of the people who actually make stuff, none of that will matter. I just find it surprising because apart from a few recent missteps—I think their marketing department really really fucked up with Southern Islands—they've been steadily improving in terms of execution for the last few years.