End regen has been planed to be nerfed for ages, and sadly cylus is no longer with SOE.  (Today was his last day :-( )

That being said it would probably be best to say end regen will go to ever4 sec (same as power and current base end regen)  and im not supprised, however it will mean a considerable hit to harmonious dps as well as regular melee dps. 

Ill be sad to see cylus go, as he was one of the few developers i personally interacted with on the test.

yeah, basically, it will totally break harmonious monks if they every get around to changing it.  We'd pretty much be down to two types of monks.

Yes currently, if you have + 5 endurance regen, you get 5 end/ sec ---> 20 per 4 seconds.  Then you add on the addition 20 you get every 4 sec from base endurance regen, that totals up to 40 endurance / 4 sec.

And again yes, harmonious are + 40% endurance cost at the moment, when they fix the cost, all it really is going to do is drop harmonious dps a bit because now they will be forced to use aum ti (-20% end cost) so that they are only +20% end cost in offensive stance.  Which has a two fold impact, it means 1) they wont be using aum kor to make special attacks come up faster and 2) they will be holding back on dps in order to conserver endurance.

Heavy dps rangers will be hit hard yeah.  Like youve said, when using a bow you dont regen endurance, and thus end regen gear was enabling rangers (and harmonious mnks) to do considerably higher dps.

Another big problem with endurance regen is that the item that adds it states it adds it to pattern (chest), which i was under the impression that it would only add to tunics, not every slot of armor, not sure if thats part of the nerf or not but well see.

On a side note, bard dots are nerfed on pvp servers.