It may. If Apple sticks to Intel Xeon W 2200 series and Apple uses the price reduction to move the base iMac Pro to 10 cores instead of 8 then it will have a multicore edge. ( the W-2255 is less expensive than the W-2145. ) The base /turbo of the 2255 and 2155 are the same though. So on single threaded drag race it probably wouldn't do any better.
There isn't a huge leap in implementation here. Slightly better clocks speeds at slightly higher thermals plus some limited instruction improvements and bug fixes.
Kind of doubtful that Apple would start the iMac Pro at 8 cores if the regular iMac was going to hit 8 cores in 2020. Plus don't think Apple would be inclined to pass along price cuts that the W-2200 series got (at least at the entry level). Just shifting to a more expensive processor closer to the old 8 core price would be the more likely move. That would mean that the iMac Pro would have fewer CPU options so the top price driven by CPU would go lower. ( which again I doubt Apple would mind much at that keeps the iMac Pro more viable. A 10 , 14 , 18 core line up. if the 18 core landed on the $6,599-6,999 price point they'd probably be happy with that. ).
The MP 2019 with 1TB drive is $6,399. The folks who put a higher value on add-in slots and memory would put value on the MP and the folks who want cheapest path to more cores and don't care much about upgrades later would go with the slightly higher price point. The folks who ant both will go Mac Pro at an even higher price point.
If this is a "apple switches to AMD for iMac Pro" , that doesn't look likely. The W-2200 is better fit to the current case design thermals versus Threadripper 3. ( Apple throwing away the case design after one iteration... is not their modus operandi. ). Going Ryzen would be odd. ( not impossible but odd.)
Is there any reason to expect an iMac Pro refresh? I always assumed it was a one time spaceholder due to the inability to get the new MacPro released.