It's funny, widgets were already a blocky way in WP. You had a block (widget) to use with a lot of functionality.
Now, it's time to retirement. It has accomplished a lot.

But I feel this new switch could be an opportunity to go further. Since so many users will have to adapt, why not in a big way?
I'm thinking on CSS Grid.
Maybe it's a good time to implement it in WP as core? (sorry if any term is a bit displaced, I'm not a big structure expert)

As it is useful to have a widget anywhere, eventually it will be very useful to switch blocks around.
We have a 'header', a 'footer', a 'content', why not a 'left', a 'right' or even a 'my-favorite-spot'?
And they can be anywhere we want with the specific blocks we want in each.
And in different locations according to media-queries (desktops, mobiles, print, etc)
With Grid (grid-template-areas) we can have these powerful way of constructing blocks.
Maybe it's too soon to implement but never to soon to talk about it.