Tough one, I think if miners pressured pools, they'd be more likely to adopt it. We have interests from a few pools already, so reaching half of the network can take 2-3 years in my rough estimate.

I find it hard to estimate a timeline. My imagination around this happens more in terms of sequence of events.

As soon as pools start adopting SV2, or even new pools show up (e.g.: Demand), we would expect more hashrate being produced via SV2.

If we start to notice a trend where SV1 hashrate starts migrating towards SV2 (even if via translator proxies, from legacy SV1 ASICs), that will be a clear pressure for legacy pools to start moving towards adoption, and everything should be a trickle down effect from there.