You could gain some outstanding marketing feature by selling it with Dualboot.
Has it ever been done before, giving user the choice?

Android is kind of mandatory as many said before to get off the ground.

Sailfish could "come" by either sending prototypes or early models to voluntary and proven porters.
Maybe even ask/inform them in early stage about possible involvement and requirements from their side.

For Android support within sailfish, put actual (kickstarter perk?) money into AnBox project.

Only involve Jolla if they move first.
You are in no good position to get a good deal with them for a new device, like you have with the tablet, because they will have much work with adaption.
Unless they are genuinly interested by themselfes or you can show (grand) sales that is.

The other options are out of my humble scope to judge about.
But if you play and dokument as open as possible, what keeps hackers away from doing theyr thing?