For me, the most obvious tier would be raid T7, to accompany DSK; the tier is light on content, with only one raid zone, and the item tables aren't complete. Much like VP and Fear complement each other, DSK and POH would fit really well in both theme and itemisation.
DSK is missing several items, so POH would be a great opportunity to fill the gaps for guilds preparing for T8.
- Plate, leather, silk and chain legs (off Innoruk/quested from killing him)
- Arms (any, DSK has none; again, can be the reward for completing the zone, similar to hands/arms slots in Fear)
- Non-rare wrists (only wrist item in DSK is All/All but is on a rare table)
- Leather chest item
- Non-rare piercer
- Rare bow (slightly better than the DSK bow)
- An extra set of helms, not ALL/ALL
- More class specific items (DSK has a few but not for every class - it would be nice to finish the list off so all classes have their own)
- A table of decent but not overbearingly powerful 8 slot augs (currently, you need to farm slot 8s from VP/POA to fill gaps).
- A 16 slot weapon aug (currently, there exists only three in the game and two of them are T6, the other is in DSK - so the best you can get is Dark Ball of Energy and Silver Box)
- A small list of slot 18/17 augs (maybe three max)
- Arrows that are better than T6 (which seem to be not a great deal better than T4)
There are probably more. Mainly, filling any focus gaps could be done as well (I may be wrong but I think some classes lose out on a focus or two if upgrading fully to DSK items; that may not be the case, though)
Just a thought. There's talk in another thread about Charasis being opened up, too. That would be equally cool; but PoH is one of my favourite old world raid zones, so I'd love to play it again

Thanks for reading.