from Metal Gear Informer
:Kojima feels he can finally create a game that captures the tension of 'The Great Escape'
Regarding Portable Ops still being canon or not:Regarding other MGS4 connections, Kojima said about Metal Gear Solid: Portable Ops; "If you change the Ops story, you have to change 4. If you change 4, it also becomes necessary to change Ops. Until Ops is finished, 4's story can't be finalized."
So yeah, PO despite not being directed by Kojima it has strong ties with the main series.
PO not being in the timeline of the official MGSV site could imply something, or maybe not since Metal Gear and Metal Gear 2: Solid Snake have been ignored in an official timeline before
and that wasn't a big deal at the end of the day.
---Kojima on MGSV storytelling and acting: Snake is not the same person anymore
-- Metal Gear Informer (via
: GamerhubTV, YouTube
)"Hideo Kojima talks about Kiefer Sutherland, characters and cutscenes, and how MGSV will use new ways to tell a story."
- Episode 007
-- KOJIMA PRODUCTIONS - HIDEOBLOG (English)
This edition of the podcast has details about Reflex mode, Ground Zeroes, Marking System and more.