Or why not AMD CPUs
Ah yes the long-rumored ARM transition. Too badI would love it, man. However, we all know that Apple is soon to migrate to their own chips. It would be weird to reshuffle the supply chain for just a couple of years or three, tops. Intel delivers custom chips to Apple, not a usual practice. It shows they have a very strong bond.
The real question is: When will be the next iMac Pro release?
The current iMac i9 outperforms the iMP in many CPU tasks, especially in single core performance and is equal in multi core. The only bonus is the better graphics.
Apple cant launch a new iMP this year, because it would kill their nMP release. Maybe there is no need for a second Pro device anymore.
Apple cant launch a new iMac before a new iMac Pro is released
Comet Lake S is the successor of the i9 9900KF iMac and is expected for early 2020.
iMac The Comet Lake S prototypes are already going around. They will bring a new socket (LGA1200) for better power management and motherboards are very close to being introduced to the market by the main vendors, with Intel 400 series chipset. Therefore, it would be sensible to believe that Apple has all the tools now to bring a 2020 iMac model to completion.
GPU-wise, I would expect for sure the 5700 and 5700XT be in the BTO version (over PCI-e 3.0 since Comet Lake, as well, doesn't support 4.0 speeds), but the base one is still missing a 5600 (I'd say), that should arrive soon. It's actually more likely than the 5800/5900 to appear in the next 30/60 days.
I think it's unlikely that Apple will offer the $400 225 W TDP Radeon 5700XT in the consumer iMac, even as a BTO. This card occupies the Vega 56 slot.
I think we might see the normal ($350) Radeon 5700 offered as a BTO option or perhaps as a standard option in a slightly more expensive high end model. Usually we see a ~$200 GPU offered as standard in the highest-end SKU.
As much as I understand the case of the TDP, it would be quite strange to market a computer that has the same GPU performance as the previous generation. I would expect the Vega 48 to be replaced by the XT, which is - I agree - comparable to a Vega 56, but cheaper (I guess?).
I am pretty sure the next iMac will not be a simple CPU bump. Therefore, higher TDP may be achieved if they implement some iMP and XDR display know-how. But again, it's just hope of a future customer.
But with a new design anything could happen. I expect a larger/better display, FaceID, increased cooling, and other nice things we'd like to see to make the machines a bit more expensive already so we'll have to see if they want to spend more money on the GPUs than they usually do in addition and raise the price even more.
“Delayed gratification” is just that: delayed gratification. Only you can decide how well today’s offerings meet your needs and wants against what might come at some unknown point in the future. At least with technology this is an ongoing dilemma. At some point you get on the train, or you don’t.Delayed gratification may pay off if there are significant differences between this year's model and next year's model.
As much as I understand the case of the TDP, it would be quite strange to market a computer that has the same GPU performance as the previous generation. I would expect the Vega 48 to be replaced by the XT, which is - I agree - comparable to a Vega 56, but cheaper (I guess?).
I am pretty sure the next iMac will not be a simple CPU bump. Therefore, higher TDP may be achieved if they implement some iMP and XDR display know-how. But again, it's just hope of a future customer.
The problem with your thinking is, your mindset is still in 2017. Originally AMD considered naming the 5700 & 5700 XT; Radeon Pro 680/690. That is because they have the same number of cores as RP580/590. The huge performance increase comes from the switch to a 7nm process. It doesn't matter that they are faster than the old Vega-cards. AMD's Navi lineup will be overall significantly faster. The Navi GPUs that will replace Vega in their offering will feature much higher core counts. Those will be arriving next year.Some of you guys are getting a little wild with the 5700 and 5700 XT predictions. I don't think we'll see either of those in either of the iMacs. They are gaming focused consumer cards and aren't as well suited to compute / workstation tasks as Vega, so I don't think Apple will put them in the iMac Pro. And the 5700 XT is too power hungry and hot to run in the standard iMac 5K. Apple could maybe make the regular 5700 work, but Apple never puts highish end GPUs in their consumer level products, so the 5500 is more likely in my opinion. The 5500 should be very close to the performance of the Vega 48, but at a much lower price. So Apple might just replace the Vega 48 option in the iMac 5K with the 5500 and cut the upgrade cost from $450 down to $200 or so. And depending on AMD's launch schedule, I could also see Apple replacing the 580X with something like a 5300 or whatever the low end budget Navi GPU will be called.
The problem with your thinking is, your mindset is still in 2017. Originally AMD considered naming the 5700 & 5700 XT; Radeon Pro 680/690. That is because they have the same number of cores as RP580/590. The huge performance increase comes from the switch to a 7nm process. It doesn't matter that they are faster than the old Vega-cards. AMD's Navi lineup will be overall significantly faster. The Navi GPUs that will replace Vega in their offering will feature much higher core counts. Those will be arriving next year.