PSX Extreme says:
At this point, Metal Gear Solid 5 will probably happen (even if it is without Snake). Franchise creator Hideo Kojima has now said it himself during an interview with Famitsu:
"I gotta start thinking about MGS5... Even though, well, Snake's story ends in MGS4. ...About MGS5, that would be something that Kojima Productions would have to make, I think."