I would not put money on Apple selling a machine whose price and performance makes existing Mac Pro owners feel like they wasted their money by buying too soon.
In 2017, Apple came out with the iMac Pro which "covered" a substantially large overlap of the Mac Pro 2013 (and 2012 ). In 2020, Apple came out with an iMac that covered the lower configurations of the iMac Pro.
The next "big screen" iMac probably will cover a decent subset of the lower range that the Mac Pro 2019 covered. The big screen iMac isn't very hot on active leaks so that probably will slide to 2022. However, it is doubtful "keeping the Mac Pro 2019 'safe' " is the primary driver of that.
At the highest, of the high end there will likely be a longer transition , but after 2 years of sales ( if there is no update) they are going to trying to artifically kneecap the newer systems so the previous buyers can 'feel happy'. If those folks had needs 1-2 years previous , then they should have bought at that time.
If I were a gambling man, the Apple Silicon Mac Pro that performs on par with the Intel Mac Pro, will cost roughly the same as the Intel Mac Pro. Whatever savings Apple makes on fabbing their own processors, they will build up to the price, not price down to the components.
The 2019 Mac Pro prices have a couple of substantive problems. First, it is about a 100% increase of where the entry-mid Mac Pro prices have traditionally been. It is was priced up and over the iMac Pro. Problem in 2021 is that iMac Pro is dead in the water... so just relatively just high ( even among just Mac products ). Apple has small "hole" in their pricing line up. There is a decent chance they'll use a smaller "Mac Pro" to fill it.
The w-3223 8 core in the entry Mac Pro originally listed for $749. if round that up to $1000 for Apple markup and still left with a chassis that is $4,999. Apple could chop lots of stuff off. Crank down the 1.4KW power supply. Drop at least half the slots. Drop the PEX PCI controller, Drop the PCI-e and DisplayPort switching distribution network, Drop the DIMM sllots. etc. The overall chassis cost could drop in half. So even if they were charging the same for CPU the overall system cost would drop substantially.
Second, not even Intel believes in the old "> 1 TB RAM tax" anymore. So at the high end those prices are likely gone due to increased AMD (and others ) competition. In late 2018 - early 2020 Intel was socking away tons of cash that they would use to "buy" their way out of not having competitive product in 2020-2021. Apple just piggybacked on that to add to their own agenda on high end workstations. ( one issue was to pay for more R&D on lower volume of sales. )
For example, if it has no slotted GPU, they will claim that the GPU component of their processor is worth the same price as the MPX GPU in the Intel machine, and then present a doctored performance comparison to show how it's actually better value.
They are more likely to point out how much power is saved ( and hence saving the planet) and quieter it is .
They don't have to doctor the performance that much if compare it to a 580X or perhaps even an 5700 ( if they only have a high end GPU option). They just have to pick on older GPUs ( of which there are several in MPX form factor from the 2019 era.) They are pretty unlikely going to be able to cover the Duos MPX options.