Yes, I was signed in Google but it's definitely the first time I've seen the visit dates.
Interesting observation. I vaguely remember seeing something like this quite a while ago, but only briefly... perhaps when I allowed Google to retain my search history. I haven't seen it since I've been surfing with search history turned off.
(Note that to turn search history off, you actually need to surf logged in, as you need to save the history preference in a cookie that can associate the preference with you. On my signed-out browser, though, I flush cookies routinely, so that never accumulates long histories.)
Is this going to increase or decrease repeat visits?
This might be something that they're testing, most likely looking at a bunch of different factors.
It should depend, IMO, on the type of search and the type of target site... and perhaps on your searching patterns.
It's perhaps a variant on QDF. Visited links on Google change color in any case* (see my note below), so a date would give me as a searcher the additional information of how long it's been and whether there's a likelihood of fresh material since my last visit. On forum pages, eg, in areas where I've been doing research, this would tell me whether I want to try a page again. It might also be useful with ecommerce sites that change prices.
I'd guess that for some kinds of pages/sites, repeat visits are a likely positive factor in the algorithm... and particularly for personalized results. But repeat visits where you back out because there's nothing new might be something that neither you nor Google desires, so a last-visit clue might be helpful.
I'm wondering if you see this for all kinds of sites, or just on sites where the content is likely to be changing?
*Note: I'm also wondering whether the visit date is perhaps being testing as an alternative to the vlink color change. I notice in your screen capture that the link is blue, but I don't know whether you've visited that page before.