How possible is that they will be needing some bleeding edge update of WINE or kernel?

If you think you can expect that they won't need to do bleeding edge updates, pick something that is easy to use for you and just choose a WM that will be easy for them

My grandma and mom use Manjaro with XFCE. Or rather they use XFCE, I use Manjaro on their PCs ;D. They don't need to update to, for example, NTSync enabled version ASAP, so it's fine with me just doing an update during some holidays for grandma and over the phone for mom.
We used to try Mint for their boxes. I was banging my head against it as always with Debian based distros and the effect was that for them the downtimes were longer. Despite our mutual hopes, mom never really got self-sufficient with managing the OS. Even with GUI based package manager. So I just migrated them to Manjaro and now we are all happier. For me the updating is less painful and is faster, for them it just works

But if you would need to educate such user on how to use some package manager to update something, then maybe there might be some differences between GUI package managers that might help you
although

for someone who doesn't know how to do much more than check their email and log in to Steam

I think it will be you doing the updating in the end