Reckon that's the point. If 4GB devices get limited, then 3GB would be more so.
3 GB would eventually get limited in some fashion, before 4 GB ones do.
They do. 1st gen iPad Air never got split view and 2GB iPads don't have active 2x split view + slide over. Granted, I think the latter may have been pulled from later betas or GM for the 1st gen 12.9 as well. I don't have that model so can't check.
Yes I know, some features are not supported on lower memory models, even if the OS is supported. However, what I was meaning by that is that some other features come to all models, which means that ones with lower memory get bogged down or even crash, or at least reload. The biggest example of this is multi-tab Safari. You can run as many tabs as you want on the iPad 2, but it runs like molasses and eventually crashes, despite the fact that tab reloads are supposed to mitigate the RAM usage.
Then again, Apple probably has learned from this and going forward they won't allow performance to degrade that much due to memory and SoC limitations. The original iPad Air stopping at iOS 12 makes sense. This keeps performance on the original Air good, and also means that Apple isn't hamstrung by having to maintain compatibility for 1 GB iPads.
However, what this also means is Apple and third party developers are free to target larger memory sizes, and in fact, Apple is already pushing this.
They did this with the 1st generation iPad Pro, releasing 2 and 4 GB iPad Pros side by side, telling developers that 4 GB is the new target. In 2017, the new iPad Pros were 4 GB across the board. Then in 2018 they released 4 and 6 GB iPad Pros side by side, telling developers that 6 GB is the new high end target. I'm guessing that 2020 will bring 6 GB across the board, although there is also the possibility they may release an 8 GB model at the high end.
Honestly though, until we get resizable windows I'm not too worried about 4GB. Even then, more RAM for multitasking is something I'd be more concerned with on the 12.9" iPad than on smaller ones. As it is, I almost never use split view on the Pro 10.5 never mind split view + slide over.
Split view is decent on the 11" and usable on the 10.5". Depends on the apps used though. But yeah, it's best on the 12.9" models.
In Safari though, it's more often getting more cramped now in iPadOS on the 10.5", because it's the full desktop version now.