I think $30 million is the average marketcap of nxt right before snapshot period. So I guess we can roughly assume the price of nxt should be declining at 1.1 % daily as time period for ardor token nears. Just a guess
That logic assumes that Nxt itself is worth nothing other than the Ardor token value, which is not true.
Even if most of the increase of value comes after ARDR snapshots, once the snapshots end Nxt is still there. Your NXT are still there. And those NXT will also give you a share of the first Ardor child chain token (the transactional token, FNX in dev discussions) when Ardor launches. This besides any news for Nxt 1.0 roadmap.
The change in Nxt valuation in the next three months should reflect the difference in value perception between NXT, ARDR and FNX. Besides the craziness of the market itself.
Remembering other things down the road besides ARDR token (and how much will it trade for once tokens are distributed) is important.