I'm sure hoping SSD will be standard in new iMacs.
Agreed. My Mid-2010 iMac whilst running great (especially with the SSD I installed myself inside) is officially obsolete in terms of wireless connectivity and not being able to get the latest OS inside (no High Sierra -> Mojave for me). I would like to take the leap to 27" 5k from the current 21.5" 1080p screen. However, Apple's policy on the HDs is the only thing holding me back as it's just ridiculous that in 2018 they are using HDD's or even Fusion drives. Sorry Apple, but if you are (officially) justifying this by saying that HDD's are handy for people who need space (whilst just about every other desktop computer has an SSD inside), why not make the M.2 SSD (which takes no extra space) the standard and make the HDD a cheap BTO option (as it's obvious you do not want a thinner chassis because you are sticking with HDD's). I know I can get the 256GB SSD drive as BTO but the price is tough to swallow (you can get a Samsung 860 Pro 512GB SSD a lot cheaper).
I'd really love to continue giving Apple the big bucks but I won't buy obsolete tech and that is pretty much what the iMac has become because the SSD option is only an expensive BTO. If they continue this trend, it's Windows for me then.