Good point.
(But those machines could replace a large number of volunteer hours.)
Did the donor of the new trails provide a budget for continuing maintenance? If not, someone will have to figure out how to spread the volunteer hours across the old and new trails. I hope the new trails will draw new volunteers.
The trailwork events I've attended at Oaks have been typically well subscribed---if you get there late they run out of implements. Which is great, you can take turns when you get a little winded. Even an equestrian or two will show up, and I once saw a hiker in the mix--though it's still 90% bike. It is a well-loved park.