Has this even happened in pokemon since sneasel and slowking got banned? Really, no counters? Our BDIF curently counters this new gimmick. Luxray lv X (you know, the most popular card in the game) hitting Palkia G for weakness, and luxchomp being awesome at trolling any kind of setup seems like they'd be pretty awesome counters so far. But hey this is just Theroymon about a card that hasn't even been revealed yet (in reference to that gengar), and to cards that don't even have a definite release date, what do I know (or anybody else) know?
Sneasal was banned when the original modified was announced ("in the box" as it were).
Sneasal was never legal in modified, therefore there was no point during which it was impossible to counter (it's like saying venucenter was broken in modified).
Sorry to rant, but so many people in these forums keep bringing up Sneasal like it was ever in modified to begin with. lol
Slowking actually did have a counter (Muk was reprinted in Legendary Collection, Igglybuff from Neo Discovery was around, and let's not forget Neo Pichu). It was banned because every winning deck had to run Slowking and fill up their bench for it to be effective (the only difference in decks was a matter of one or two pokemon).
If you want something more spot on for this kind of topic, how about the days of Feraligator with Riptide (Neo Genesis)?
Everything had to be gatr or a direct counter to gatr that pretty much died against anything that wasn't gatr.
What if your luxray goes to the lost zone before you even play it from your hand?
What if SP decks have to be more careful with coming into play powers because they can't afford to be wasting bench spots against a lost deck?
What if the set gives us more lost zone friendly cards that aren't weak to lightning?
There are too many variables to be saying that one card is going to stop lost world from being any good.
We only know of about 25% of the set so far, so it isn't exactly crazy to think that there will be more lost zone stuff coming.