We'll see, but I don't think Apple are going to undercut their iMacs with headless cheaper desktop and I think that the $2,499 price will remain as it has for many years.
There is a significant gap between the $1999 where the iMacs end ( excluding the BTO options. those just muddle the price continuity between models) and the $2,499 'starting line' for the Mac Pro.
Using $100 gaps could put three products in there: $2099 , $2199, $2299. Even with $200 gaps could put three with small overlap on the last: $2099 , $2299 , $2499. If entry Mac Pro shifted to $2599 there would be no overlap and Apple would be OCD happy.
One of the major problems the Mac Pro has is it is not using the full $2000+ price zone it should have control over ( presuming there is a product pricing exclusion zones policy at Apple... which lots of evidence backs up with 13" laptop logjam aside. One of those 13" isn't going to survive. ) That just suppresses Mac Pro sales for no good reason.
And trying to goose iMac BTO sales so that the top CPU + top GPU option is still below the Mac Pro is short sighted.
Maybe it'll be better value this time or maybe it will be cheaper, but they know they can sell Macs at that price.
If they were selling enough at that price to demonstrate desirable growth they would have updated the product long before now. The sales have been unsatisfactory. That's why the product almost died. To keep with exactly the same strategy is inviting doom for the product. There is a substantively higher probability here for a change precisely because what they were doing before did not work. Something is going to change.
That could be price or feature mix or some combination but something.