The mini's processors are all "special package" ( BGA not socketed ). They aren't necessarily coupled to the retail market and may fall into "extended support" . The 10 of millions of CPUs would probably be several years worth. Mini volume is not that large. That is dual edge sword. Either Intel looses interest faster or optionally can fill apple's needs with 5-9 days worth of work ( i.e., turn of the spigot to everyone else 2-3 weeks in advance of apple and give them the last batches. It isn't like Intel would need months and months of production to do the mini. )
Apple doesn't have forever on the Mini. If Apple cuts the Mini back to what the lower end Macbooks are on ports ( two Thunderbolt) then they could perhaps go more quickly.
Eh? Not even hardly. First, Intel hasn't even replaced the Xeon W3200 series at all. So they'd be extremely hard pressed to stop selling it any time soon . There isn't an "Ice Lake" Xeon W replacement coming before 2021. Intel , for better or worse" , appears to be throwing all their "big die" Ice lake wafer starts at the largest core count dies first to fill Xeon SP orders with much higher margins. Until they fill that initial peak demand bubble they'll kick out he Xeon W (3300 series likely) until further into the future. Probably a quarter or so into 2021.
The W3200 series first shipped in 2019
Products formerly Cascade Lake product listing with links to detailed product features and specifications.
ark.intel.com
Intel® Xeon® W-3225 Processor (16.5M Cache, 3.70 GHz) quick reference guide including specifications, features, pricing, compatibility, design documentation, ordering codes, spec codes and more.
ark.intel.com
The Xeon W2100 series of the iMac Pro is on thin ice. ( 2017 launch time) , but there is a W2200 Intel/Apple could kick the can with that is drop in socket and chipset compatible with . Apple jumped to the price reduction that the W2200 brought, while still squatting on W2100.
The Skylake-x (the consumer version of the 2066 socket) is being dropped by January 2021 , but Xeon isn't necessarily on the same cycle.
"... The last shipment of Skylake-X processor is expected a year from now, on July 9 2021. ..."
https://www.techradar.com/news/intel-is-discontinuing-its-9th-generation-skylake-x-processors
The W2200 series is based on Cascade Lake. It only started limited shipping in Q4 2019. It probably isn't being turned off in 13 months of time (before any replacement ships. ). the W2100 is being discontinued in part because the W2200 has shipped. When the 2200 is 6-8 months into service life time then can start talking about when he predecessor gets dropped.
Apple could tweak the iMac Pro later this Fall with a W-2200 and some GPU upgrades to kick the can into 2022 ( along with the Mac Pro ). If there is a substantive time gap to fill there isn't much upside to moving the iMac Pro sooner.
The Mac Pro ( iMac Pro ) are probably last. The I/O infrastructure that should be there is so entirely disconnected from that of the iPad Pro origins of what Apple is starting with that it is probably tagged as second generation AS implementation. Apple needs a SoC package that even does moderate PCI-e v3 (or v4) interaction with a discrete products let alone very high double digit lanes and quad digit RAM capacity. Apple jumping to that shortly out of the gate is unlikely.
A one or two port "wonder" MacBook would be easy with their past work. However, even a step up to a two port Thunderbolt , quad port 3.1 Gen2 USB-A system would be substantive move up in complexity for them.
