I won't be pessimistic now. But ever since Kojima said that this game would contain less cutscenes, and less voice acting by Snake I became quite worried... I don't doubt this will be GOTY material, but it may not be "Metal Gear" material.... =/
If anything it's going to be more like Peace Walker where everything is fleshed out in the tapes. You'll get the main story but no doubt monologues and backstory will be fleshed out with the tapes.
I guess it's the line Kojima had to tip toe. Many people complained about long cutscenes. Especially in 2 and 4.
Personally I don't mind this approach. I can deal with tapes. It's no different than codecs really.