The first stretch goal was larger SD card support. That one was done, though with ext3 support instead of exFAT, by popular demand.

The split screen is last mentioned on the roadmap in August:

So on that information it would be sensible to assume that didn't get past the design stage before it all went pete tong. At the last mer community meeting (which are increasingly turning into Jolla news days) they said they weren't done with reorganising the roadmap after losing so many people, so I guess we just have to wait and see. I should imagine it's definitely still on the to-do list though. Jolla don't intend to abandon support for tablets just because the Jolla one is finished. Sailfish now supports many different sizes and resolutions.