I'd expect averages might drop in spots, and raise in others, regionally. But the variance will be all over the map. And already is.

Summer heat waves, droughts, intense tropical storms.

And then winters with unusually warm days followed by record lows.

For Northern/Western Europe, with the gulf stream interrupted I'd imagine the could expect a climate closer to what the northeast of the Americas already get: erratic inconstant weather patterns with lower lows than they're used to.

Remember that the northeast and midwest is quite a bit further south than many western & northern European cities, but suffers far more brutal winters.

Here in southern Ontario, we're at the same lattitude as northern Italy or south of France, and our summers can be just as hot, and growing season about as long (and way more humid). ... But in the winter there's episodic lows below -25C, -28C. And I can tell you, you can't easily grow e.g. vitis vinifera grapes with those patterns, and certainly not figs, citrus, etc.

I don't think Europeans are mentally prepared for this, if it's coming.