Should there be concern about breaking Gutenberg updates to extended core blocks?

Luke,
I’ve only done some but I’ve had some existing block styles and block style variations break after updates (examples 1, 2).

So far, I haven’t found many proactive things to do prevent your blocks from breaking in the first place besides this list on backwards compatibility and would love a core Gutenberg contributor to chime in here (although they likely won’t read this) with any additional advice.

That said,

One thing that I’ve noticed though is that the changes won’t affect existing published content on the front-end that has already been published but the ‘breakage’ of a block will occur within the block-editor when your content editor goes to update a page/post that contains the said block; because the block needs to be regenerated.

Lastly, this isn’t so much proactive, but reading over the dev notes can help you be aware of issues immediately before they become a problem for your clients.