I have two theories about Marc's departure, but I do want to stress out that it is just speculation, so we should not jump to conclusions without statement from Marc himself. The two theories are:

• Tighter investor control - the split to two companies (=killing the hardware division for those who didn't figure it out ) was quite logical, but it must have been a result of investors running out of patience. I think that this change wasn't the only one - Jolla is probably under a closer watch of investors since then and the lack of creative freedom could have driven Marc away.
• Sailfish 2.0 - it was created as a compromise, with no real design path, abandoning some design principles that were crucial to Marc - "no tiny buttons", and most importantly the single hand use. Especially if you're a left handed person, you cannot get into Events, unless you sacrifice going to the app switcher. And even for a right handed person, accessing events view is a stretch, not really following the single handed approach of Sailfish 1.x.

OT:

There is also LuneOS - I would take it as the second choice after SailfishOS for its multitasking capabilities and webOS legacy. I don't really like what it's based on (Yocto - embedded Linux platform), but it uses the technologies we know from SailfishOS:

• libhybris
• Linux 3.x
• Wayland
• Qt 5.4

It features monthly releases too. You should check it out