i can still see antpool above them, so they are not that large
Antpool is also a significant chunk of third party miners, not just their own farms. There's quite a few threads around from people leaving BTC Guild due to shutdown going to Antpool, people who don't understand variance (or prefer more stable, albeit smaller, payouts) leaving other small pools for Antpool.
obviously those chinese pool are scary they keep growing at high speed
F2Pool has been seeing a bit of a decline, but the only one really 'growing at a high speed' at this time is BitFury:
, but they are intelligent enough(i would hope) to not reach a dangerous %
Together they already have a 'dangerous %', see also the recent snafu resulting from glitches they shared
Individually, presuming there'd be a market panic, I guess they could increase fees (short term win for them) and wait for miners to shift over to other pools, but that hasn't always been to great effect in the past. There were fears Ghash.io was reaching 51% in the past.. the first time people were discouraged from using, and some left... but most (and a good chunk of this was BitFury) stayed, and eventually people came back. The second time around BitFury ended up leaving, and then more people left until it was almost completely marginalized.