I can't prove it but I believe there is a scribal error in the Revelation passage that excludes Dan because the way it is structured it makes no sense. See http://www.nccg.org/088.html for a response.

Ezekiel's vision tells us that Dan has a portion in the north of the land - this definetely refutes the interpretation of Dan as a 'lost/forsaken' tribe, though the question still remains whether the tribe of Dan (lit. "judge") has a different role than the 144,000 witnesses, in the end times.

A scribal error is actually possible.

Exactly - Ezekiel's portion for Dan establishes this as a bona fide tribe in perpetuity. We should also remember the lengths Israel went to in order to preserve the integrity of the 12 tribes - I am thinking of the rescue of Benjamin from the verge of extinction. Dan is all over the world and has played a substantial role in the history of Europe and elsewhere.

Christian said:

Ezekiel's vision tells us that Dan has a portion in the north of the land - this definetely refutes the interpretation of Dan as a 'lost/forsaken' tribe, though the question still remains whether the tribe of Dan (lit. "judge") has a different role than the 144,000 witnesses, in the end times.

A scribal error is actually possible.

Could there be a relation between the Holocaust and the Tribe of Dan's absence in the end times?

Clearly the Tribe of Dan receives land in the Millennial Kingdom according to Ezekiel's vision, and this land must have a population at some point, though perhaps like Dan historically got their land in the north slowly after much entanglement, so maybe Dan will receive their land slowly, while repopulating their numbers thinned by the Holocaust ?

Possibly but I don't think so. The research I have done suggests that Dan migrated principally to Denmark and Ireland - and there are plenty of Danes and Irish about! Yair Davidy believes they are also the Celts which makes for man more.

Christian said:

Could there be a relation between the Holocaust and the Tribe of Dan's absence in the end times?

Clearly the Tribe of Dan receives land in the Millennial Kingdom according to Ezekiel's vision, and this land must have a population at some point, though perhaps like Dan historically got their land in the north slowly after much entanglement, so maybe Dan will receive their land slowly, while repopulating their numbers thinned by the Holocaust ?

This is of course assuming they are actually absent.
There is an interesting theory regarding Dan's name meaning "Judge", signalling they have a role separate from the "Witnesses" - but this fact is not being very descriptive, and can be taken many ways.

The main idea behind the Holocaust theory was that Dan was to a large degree Askenazi, German and Polish/Slavic and was intermarried with Judah, and actually has less than 12,000 members in the end times. Once again, this is only speculation.

If that wee true, then all the other tribes would be limited to 12,000 too, yet this is not a final tally of the umber of tribal members but a group of the ruling class.