Everyone else having already established that this is all speculation, I would speculate that devices that use officially licensed Spotify Connect will work out of the box. You really don't need that much more space to buffer larger files. The devices may need a firmware update as, presumably, the SC software on the device will need to be updated to support the new setting. So, be sure that it's a company that is likely to update regularly and/or that the device is not older than a year or two. Devices from larger companies like Cambridge Audio, Bluesound, NAD, etc. probably all fall in this category.
Devices that depend on Librespot won't work right away. Librespot works by reverse-engineering the SC protocol, so the developers are going to have to wait until the update rolls out, then they'll need to figure out what the changes were, then implement them, then test them, then release them. Then the device manufacturers will have to incorporate the updates into their software/firmware releases. It'll happen eventually but it'll take longer, unless there is some possibility for Spotify to block Librespot from achieving that (doubtful). Devices from smaller companies will fall into this category. I know my SOtM sMS-200 uses Librespot, and any Raspberry Pi-based solution will use it as well.
Really old devices can just forget about hi-res compatibility since they depend on older software called libspotify. No way that I know of to tell which software a device uses but anything older than 7-8 years IIRC is probably on libspotify.
