We'll have backups, but it will be complicated
We barely understand the brain. Neuroscience has only left the "let's touch brain regions and see what happens" phase a few decades ago. Scanners do now have resolutions of 0.1 mm, about the diameter of a neurons body. This probably has to improve by at least two orders of magnitude to allow any kind of actual monitoring and deep understanding of the activities. Additionally, a good theory of the mind won't hurt you either.
My intuition tells me that simply scanning a dead brain might not be sufficient. We aren't really made for long periods of inactivity. You might need to use generic engineering and supporting chemicals to even enable a scan. While one commenter claimed that the brains structure isn't enough to restart the "person", the cryogenic wood frog might disagree.
So just casually uploading the mind is probably out, but you can assist the backup or transmigration process in a number of ways. Genetic and chemical options might make it easier. However, I personally think digital options are quite important. Mind uploading is about crating the best possible modle of yourself. Something that functions, acts like you, is perceived by others as you and has a soul/consciousness/a sense of self (take a pick, these are probably all equivalent). Funnily enough, if the copy is you is probably going to be determined by you own beliefs. If I think a copy is a legitimate continuation of myself, it will believe and act that way. I I consider it to be a mere copy...
Going back to the digital options, you might want to use constantly active brain scanning via probes and external sensor feeds matching your perceptions and attention to train an AI. This will be used as a close partner ana assistant and if you die, it provides a valuable data point for recreating yourself.
With all that said, I view mind uploading as a Big Data project. The current state of the brain and it's encoded memories are probably necessary, but not sufficient. Especially if you are dealing with a dead brain. A live one... maybe. But historical and environmental data might be vital to the process. However, you might want to consider if a full copy is always desired. Sure, it's nice for a backup and if you want to migrate into the digital realm, but lower fidelity copies have a place as well. In Revelation Space author Alistair Reynolds differentiates Alpha (full copy), Beta ("low" fidelity copy) and Gamma (AI immitating you from behavioural data) copies.