Extremely high odds those incentives will remain next month...Was reported there were 6K+ Volts sitting on the lots so it wouldn't make sense to abruptly stop the incentives...Also the Bolt is out (in certain states) and while some criticize its looks, front seats, cost or feature choices the driving experience get rave reviews so some would be Volt sales may buy a Bolt EV instead...
That's all true but waiting is the wrong answer. It's the wrong answer even if your prediction comes true, which is what I'd predict as well.
The problem is you're trying to gain a couple of hundred bucks while potentially losing a few thousand. The worst that happens if you pull the trigger now is you end up with three extra Volt lease payments. That's a couple of hundred bucks a month. However, you may be able to offset that by getting a 10K lease rather than a 12K lease since for three months you won't use any miles. So let's say you're out $400. If just one of the $1000 incentives goes away you're down $600. If $3000 goes away you're down $2400. You're saying it's likely the incentives will stay. I agree. However, I'm less sanguine they are 4X times or 6X times more likely to stay than go. I'd be OK assuming we'll see the incentives next month, but after that the visibility is poor. And the amount we're talking about is so minor.
The psychological aspect is that when people miss an opportunity they always regret it more than they should. Have seen this many times, more of course in the financial sector. Once people miss an opportunity they never want to "lock in" their losses. They wait longer and end up making it even worse.
FYI when I got the ELR I had a few months left on my Leaf lease. I got it despite the fact the common wisdom was that there would be better deals. Turned out common wisdom was wrong. The ELR was never offered at that low price again. Decisions under uncertainty and all that. Or, as Yogi Berra famously said: "It's hard to make predictions, especially about the future".