As topic title, hasnt been any mention of this for months, at least last year.

Nothing. Its waiting for publishers to release titles that they're willing to enable GoG Connect with.

Giving too many titles for free via Connect is not the best business practice. It generates no extra direct income and personally I doubt it will motivate people to buy games via GOG instead of via Steam (I think it will be the other way around. People buy it on Steam and hope they will get a free version on GOG).

I have 753 games on Steam, yet I am against GOG Connect because I think it is not in GOG's interest. The market share companies are interested in is games sold, nog games given away.

Not really, as one would have already purchased that game already, so unless people are going to purchase every single game they have multiple times (yup i have done this a few times, some knowingly some not, but many in bundles).
Now I am out of work (Due to health reasons) I can no longer do that so if i purchased a game in steam i will not purchase it on any other platform (Origin, Uplay, GoG etc).

The pattern seem to have it during big sales.

Yeah, high five!

To minimize damages, GOG usually waits until enough people have bought the game also on GOG, then they release the game on GOG Connect. If they did it earlier, then those said users wouldn't have bought the game from GOG since they had it already on Steam, and we can't have that!

On a side note, I bet there is some interesting data collection & analytics going on every time somebody connects Steam and GOG accounts, that'd probably profit all parties involved. I very much doubt this process is just a "giveaway".

Yes and question is since GOG Connect is limited time offer - how many percentage of people are regular GOG users and how many new ones we get..

One possible solution to that could be having Connect promos where instead of getting 100% free games, you would get let's say 95% discount.
Those who want to get DRM-free versions of those games probably could spare those few cents that they would cost, and it would create some profit for GOG and publishers, even if marginally small.

Not sure if that would make any customers to shift from Steam to GOG, but presumably that would at least be enough to cover whatever costs there are to run Connect.