Whitelist will soon be the only way to go. Blacklisting approaches are rapidly beginning to fail, as we are seeing. And no it is not "copying Comodo" the entire industry has been discussing this for years and years now... problem is no one wants to stop a good thing... (read: the cash cow that is blacklist apps).
Cloud scanning? No. That is totally absurd and useless. On my own lan perhaps, but to some remote server controlled by someone else while I try to protect OUR proprietary resources? No effing way. Sorry, that will never happen, I'll just cut the connection forever when the day comes that is the only option.
Sandbox? No. That never goes well. Write your own OS if that is what you think is the solution. If it is on the whitelist it runs, if it is not it does not. That said, the USER needs full control of the whitlelist. Bur first you must qualify the user... can they handle it?
And can we please stop calling it a cloud? It is goddamn remote server (or load distributed cluster), not some airy fairy cloud... Can I puke now?
Ultimately the solution will be government regulation and licensing as was required for motor vehicles. People need training and testing before they can be allowed to use powerful technology. No pass? No internet for you - you too dumb.
Sometimes I think I just should not read forums... look what it does to me.
edit: taking the rant a few steps further... all AV products for windows do not have much of a future at all. Because windows has no future: it appears to me that kernel development stopped with Win2K. Vista and 7 are convoluted task schedulers written around an aging and frail kernel. Take a look at the default scheduled tasks in Vista and 7 and you will see what I mean. It is pretty clear that they have lost the talent that was capable... all they have now are java and .net grads who couldn't manage memory if their life depended on it. Whitelisting on such a platform will also become unmanageable because of its design and lack of kernel development. Apple is no solution either, prohibitive costs and monopolisitc tactics that microsoft can only dream of. I opend an apple case in the early nineties - not a single recognisable component inside. Useless, I thought, and they are still for all but the very rich and very limited application needs. Linux is no answer either, it would have been if Matrox had won out over ATI, but no, everyone has to be able to play the latest version of nude beach volleyball from Activision complete with the latest trumped-up video card requirements... ATI killed Linux. Matrox was so superior from the get go - I have no idea how ATI won... they were incapable of drawing straight lines on screen in the Rage/98 era... yet somehow... they win, and destroy Linux's future on the desktop in the process. Sigh... i think I'm done ranting now...