As you may have heard while back, Sony had acquired a Cloud gaming service named Gaikai, but until now we never knew what plains were laid out for them.
According to the article, the PS4 might be able to stream PS3 games through Cloud saves, so no need for a special backwards compatible edition of the PS4, no need to put the disk in, just sync your Cloud saves to your PS4 and play.
This definitely sounds like a smart move by Sony.
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I'd rather the PS4 have backwards compatibility. Sony are just trying to re-sell you games you have already bought. Besides; - Stream quality will be low - dat horrible input lag