Do you absolutely NEED to complete Prophecies or EotN to do the GW Beyond Quests?

Because I only finished the Asura part of the EotN missions and I was still able to view the Trial of Zinn and do the Keiran/Gwen missions.

I know for sure that for WiK content, you do definitely either have to finish eotn or proph

The Keiran/Gwen is tied only to eotn side I believe, i.e, you can pick up quest directly from HoM

Taken from official wiki about War in Kryta

http://wiki.guildwars.com/wiki/War_in_Kryta

"War in Kryta content is available only to characters who have completed the Prophecies or Eye of the North campaigns. If you have completed Prophecies you must also own the Eye of the North expansion."

About Hearts of the North quests also from the official wiki

http://wiki.guildwars.com/wiki/Hearts_of_the_North

"Hearts of the North is available only to characters who have completed the last quest of the War in Kryta content, The Battle for Lion's Arch and have subsequently reported the disappearance of Lt. Thackeray to Gwen in the Hall of Monuments."

And when it comes to Winds of Change, when it comes out the only requirement is if you have beaten Factions.

To answer your question, it is simply a "yes."

In regards to what you have done- regardless if you do that small Keiran/Gwen quest chain or not, you are still eligible to complete WiK+HotN. The Trial of Zinn becomes available (straight from the wiki) upon "completion of the quest Zinn's Task or completion of The Knowledgeable Asura portion of the Eye of the North campaign."

at the moment there are two parts of GuildWars beyond out.

War in Kryta: Requires you have finished either prophecy's or EOTN.
Hearts of the North: Requires you have finished war in kryta (so also prophecy's or EOTN.

The not published part is announced under the name Winds of Change and will be in Cantha. It has been announced that you only need to have finished factions for it. There isn't release date known, my personal expectation is that it will just be released.

If you have finished Propecies you would also need to finish the Asuria, Norn, and Vangaurd missions. I was able to do the WiK missions without having Heart of The Shiver Peaks, Destructions Depths, or A Time for Heros completed.
btw the Norn, Vangaurd, plus last 3 takes more than 3 hours.

Err do you mean the current wik or pre buff wik as ive done wik on a chr who hadnt finished any of the 3 sides.All you need is access to vlox falls for the trial - or thats how it used to be before the change.

Keiran appears in Ice Cliff Chasm as soon as you complete the Vanguard missions arch.

You can view the Trial if your character has completed the M.O.X mini missions even before you completed EoTN.

So, it's definitely possible to do it.