I'd definitely continue to work as if Google didn't exist.
And you will.
Being marginalized by Google is nothing new. It may or may not be a bad thing really, it just depends on who you talk to.
I do the WMT mostly for clients who want it .. When WMT first started I remember how fast everything was .. These days it appears that Google has trouble keeping up even with itself. WMT updates quite a bit slower now than it used to it seems.
Even still .. I've found that if Google knows where you are and what you do, you'll be fine. It might not be necessary to have added all of those bells and whistles that Google offers, like for instance ... a sitemap.xml will be found regardless of whether or not you submit it, and, any good webmaster that's in charge of his or her own hosting environment and files is going to know if something has been added without their permission.
You don't need Google to tell you things you already know.
.. as a matter of speaking, I too have been considering being rid of G+ and Youtube and Gmail for a while now. I'm not mad at Google really, I just get tired of the distraction that those things somehow seem to provide throughout the course of the day. I've never done the analytics and I don't do the Adwords at all either (big waste of time).
since 2004 I've resigned myself to writing for the visitor .. Long before Google ever mentioned that I should.
I made it through tons of Google Algo updates unscathed .. and even now I hover anywhere between 2nd and 4th page on any given day with just my own stuff. I'm local/regional and most of my clients or the community already knows who I am, where I am, so I haven't been, and won't be, too worried about never making any money.
Keep your chin up ... You'll be fine, regardless of, and even in spite of what Google does or doesn't do.