Essence Holes exist under the HotPatch errata for now. They weren't in Core in SR4 either.
Skinlink, on the other hand, was in Core. And anything dropped from the same book is likely dropped forever.
(You know, with the wireless bonuses added to the game, I'm not entirely sure why skinlink was removed anymore. If they'd given us a system or suggestions where wires are risky and can get caught on things or damaged, I'd understand, but if the sole advantage is not having a visible wire, and you still lose out on the wireless bonuses, I don't really get it anymore. In SR4 it was overkill because you could avoid using visible wires and would have a dozen items skinlinked, but in SR5 the wireless bonuses already punish you for avoiding being hackable.)