There is a W 2200 series apparently floating out there also ( probably shipping matter of month(s) after the X series so that Intel can work through their 14nm capacity issues. )
A well-known hardware leaker has posted specifications for Intel's yet to be announced Xeon Glacier Falls-W workstation processors.
www.tomshardware.com
Unless Apple is going to update to the new versions, I would expect not. The price discount for the W 2200 probably will not be as much to the X series (even though basically the same die with features turned off/on). One of the features turn on for the W 2200 series will probably be higher memory capacity. Intel has a track record of charging more for that. ( so in this case that would be the price drop discount would be lower. I think the 2200 will go higher to maybe max at 1TB but not increase the price. Or stay at 512GB which is still higher than the new X series. ). Obviously ECC would be a difference also.
So there may be some discount but probably not 50% sized one. If it is a small double digit one then Apple would more likely just 'eat' it themselves.
I don't think Apple is going to update the iMac Pro due to their track record inability to walk and chew gum at the same time. ( can only do 2 or so Mac upgrades in a year and put rest of product line on coast. This looks like a coast year for the iMac Pro. ). So if there is no major hardware change then it is highly unlikely Apple will change the price. ( it took from 2013 -> 2017 from them to change the price on the Mac Pro' ~3.5 years ).