I wouldn't jump to conclusions yet on the new terrain engine. No guarentees that it will play fine on older computers, but no guarentee that it won't either. At worst some players might have to upgrade.
I am in the crowd of lower end computers, but I am not fretting yet. I know when HTC is done with the update they will post new minimum required specs if needed. And like Spikes said, computers are becoming more affordable to play games like Aces High. HTC has taken care of this community for over a decade making sure to keep everything playable on some of the oldest systems. I highly doubt they will alienate that part of the community at one of their biggest moments in their companies existence.
<S> and I hope to see you return when able.