While Dream World is shutting down for Gen V, there is more than one month left. This information is on the Pokemon GL front page.
The Pokemon Global Link service for Pokemon Black Version, Pokemon White Version, Pokemon Black Version 2, and Pokemon White Version 2 will be closing completely on Tuesday, January 14, 2014.
What will be happening in October is a phased closing of the current Dream World. No new registrations will be allowed, and no new game cards can be added for existing members.
In December, tucking in Pokemon will cease as a feature for Gen V.
There is a new Pokemon GL for Gen VI,
which is expected to launch in October
along with the X & Y versions.
So yes, without Dream World, this will mean the end of Hidden Abilities in Gen V with the exceptions of Hidden Grottos, but this is not confirmed for Gen VI, as there will be a new Pokemon GL linked to X & Y which will most likely have Pokemon with hidden abilities.
Notice about Gen V GL