I believe Verizon is currently deploying ONLY mmWave.
I think Verizon sub6 rollout is somewhat dependent upon them shutting down the older "CDMA" system. That is in progress but not turned all the way off at this point.
While T-Mobile’s President of Technology Neville Ray threw water on Verizon’s dynamic spectrum sharing (DSS) plans on Thursday, Verizon said it’s sticking by its prior public commitments. | While T-Mobile’s President of Technology Neville Ray threw water on Verizon’s dynamic spectrum sharing...
www.fiercewireless.com
Short term, yes... it is just about all mmWave. But it isn't wholly dependent upon mmWave either over the long term. Apple's 5G iPhones aren't coming until much later in the year. And much later in the year is when the 'CDMA network' is flipped off. There may not be as huge of a gap there on Verizon network as there is right now if talking Feb-June 2021 when these 2020 iPhones would certainly be in use.
Verizon doesn't have as much of the spectrum breadth as the new T-mobile/Spring combo does. But that new combo has to get a merged network deployed. ATT has they own issues. The quirk that all are having to deal with is getting sub6 up and running concurrently with the older more legacy system they have going without throwing gobs of "new" spectrum at it. ( and how to get more "new" spectrum. For Verizon it looks like they are going to try to use more 'recycled' and/or 'shared' spectrum. )
If there is an objective to keep a phone for 3-4 years then where Verizon's network is right this minute in early 2020 isn't likely a good match to where Verizon for most of that 3-4 year span. For folks who churn their phones on a 1-2 year window it won't matter as much.
I'm buying a Samsung s20 which lacks mmWave support but has the lower frequency 5G hardware. I'm on AT&T which barely has a 4G presence here in the boonies so it's kind of moot for me for another couple of years. (I'm not buying it for 5G)
If too far into the boonies to get dense higher end broadband backhaul then 5G probably isn't coming regardless of what is on the towers.
Verizon customers who want their 5G where Verizon 5G servicr currently exists are going to have to be happy with big phones like the S20+ and S20 ultra because it's mmWave only. Which personally I think is annoying and crazy of Verizon, but what do I know.
Temporary.
"... Samsung’s 6.2-inch S20 5G ($999.99) smartphone currently only supports the low and mid-band 5G varieties, but Verizon said it will
start offering a version of the S20 that works with mmWave spectrum in the second quarter of 2020. ..."
Samsung Electronics on Tuesday introduced its new Galaxy S20 5G lineup of smartphones, including two 5G models that are the first capable of tapping both sub-6 GHz and millimeter wave spectrum band | Samsung on Tuesday introduced its new Galaxy S20 5G lineup of smartphones, including two 5G...
www.fiercewireless.com
Anything the size of an iphone 11 on down apparently can't accommodate the mmWave antennas yet. Though Verizon said they will be releasing an mmWave capable S20 toward the end of the year somehow. If they can find a way to fit mmWave antennas into an S20, then Apple will be able to do it, but like this article says, they'll probably have to buy that capability.
The s20 isn't a small-midsized phone in the classic sense. It is still big ( although the "norms" folks are using to judge size are shifting over time. )
s20 5G 151.7 x 69.1 x 7.9 mm (5.97 x 2.72 x 0.31 in)
www.gsmarena.com
iPhone 11/XR 150.9 x 75.7 x 8.3 mm ( 5.94 x 2.98 x 0.33 in )
iPhone 8 138.4 x 67.3 x 7.3mm ( 5.45 x 2.65 x 0.29 in )
Compare features and technical specifications for iPhone 15 Pro, iPhone 15 Pro Max, iPhone 15, iPhone 15 Plus, iPhone SE, and many more.
www.apple.com
Apple has a probably a more rigid frame ( which takes incrementally more space) but the 11 (and XR) are approximately the same size as the S20 ( 5G or not.. the 5G s20 isn't any bigger).
for the iPhone 8 sized phones ( the new iPhone 9 an the probably the 'plain' iPhone 12 ) mmWave is probably an issue. But it shouldn't be a rocket science project to put it into the 11/XR sized chassis.
It seems like they wouldn't have the time to design their own hardware and put it into production by the usual iPhone release schedule. And they're still probably wrestling with issues from the virus in China. It will be interesting to see how this all resolves.
Apple could still do their dog and pony show in September and release very close to the end of September to shortages. But yeah if they didn't have a largely complete alternative model working before the virus shutdown hit .... that is likely a timeliness issue ( or a shovel buggy product out the door issue. )