Estimates from where? If the Dev uses a private source *cough*mega*cough* or does p2p sharing they cant estimate with out gathering data. China isn't going to allow Unity to go strolling around its networks to passively gain that data
It can't retroactively apply and doesn't apply to already released games. They have said this is for new unreleased works. they also wont force this on any major studios who have lawyers on staff or retainer.
Almost all EULAs fail in court. Problem is the cost to litigate it for the user, and since companies know this they abuse it
It's not suicide unless this becomes a bud light level event where 40% of the market share walks away. To much tribalism on unity vs unreal and whatever the mobile competitor is. In fact this proposed pricing structure could remain if they make some minor tweaks like saying "on mobile releases" , changing the install quote to a rolling 12 months, and/or increasing the project income level from 200k per 12.