I've always found it's best not to have a "special" kind of account and something tells me a legacy G suite -> consumer account is going to have some holes/inconsistencies that would be hell to deal with.
Migrating back to a regular @gmail.com account has been something I wanted to do before they even announced this shutdown TBH.
This new option is still a no-go for me and doesn't address the primary issue of keeping a custom email address at no additional cost.
I'm not certain they've correctly interpreted that. The source says "This new option won’t include premium features like custom email", which I think may be different. I suspect that means keeping the email address, but losing some of the ability to manage multiple email addresses as an entity.
I'm not sure what's included there, but I think color and design schemes are one of them. And I think you'd lose the ability to have a catchall email address -- something I actually use and like, and would have to consider. But I used it mostly as a spam trap, which is less important now that spam filters are better.
So it sounds like what you'd get if you had a traditional email account with some other provider and used it as your Google login -- which comes with Gmail, Google Docs, Google Pay, and a ton of other things. You don't lose the address -- at least, not the actual addresses attached to accounts, as opposed to the myriad fake addresses I have that end up in catchall.
I think the issue was that there was lots of uncertainty for people that actually want to keep their Google account for Google Photos other other products and that do not care for the custom domain (anymore). The official wording before this change was: “upgrade and pay or ..... Photos ‘may’ not work anymore”