My understanding is that I will inherit *most* of Jane's estate, but there's a non-trivial amount that's up for grabs legally. It's unambiguously clear that Jane intended for me to get everything, but we kept putting off actually formalizing that. We finally got a lawyer in the final weeks, and Jane dictated the instructions for a will to that effect, but by the time it was drafted it was too late: the last week she wasn't coherent enough to sign it, and in the final days before that when she *was* coherent enough, she was too emotionally fragile for me to push the point. (I was damned if I was going to upset her over money.)
The time to deal with such things is when it doesn't actually matter, when you can think about it clearly and calmly without it slapping you in the face with your own mortality. So seriously: if you have a spouse, or kids, or parents, or indeed any opinion at all about what happens, just go do it.