Spoiler
In the Sagas, Ragnar was killed in England by being thrown into a pit of snakes, and we saw way back that king Aella (the one who looks a little like John Rhys Davies) is keeping one ready, just for such an occasion.
I really like this show. It's got an amazing intensity that seems to be always on screen, regardless of what's happening or how many decades we've suddenly jumped forward (It's weird to think back to season 1, upstart raiding farmer Ragnar taking on 'the man'). I can't think of a single miscast part, everyone in it is utterly assured in their role.
I do miss Ecbert though, I'm very much looking forward to seeing how England has developed in the timeframe. I assume we'll see a recast 18 year old Alfred ready to repel to heathen!