Where do you stand on the 5196G? Is it worthy of its historical lineage?
The 5196g is the Patek I like. Discreet elegance that you only glimpse under the sleeve. A path that modern Patek has largely lost. I don't like the 6119.
The mouvement should be bigger, for sure, but this is not a big deal. The only drawback for me is that I find the watch overall a bit too greyish. But nevertheless, a very beautifull watch
Do you value proportion and purity over modern scale and display casebacks?
Absolutely.
What other Calatrava references do you believe deserve more attention?
I'm an absolutely fan of the 5227g. One could argue about the date, it's not a problem for me. One of most beautiful watches ever, for me.

And finally: does the end of the 5196 line mark a shift away from Patek’s core identity?
Yes. But the 6196 gives hope.