In my home town back in Russia they now easily grow the stuff of my unreachable back then in USSR childhood dreams - apricots, cherries (the large sweet ones). The children there though don't do backcountry skiing like i did 40+ years ago because there is no snow these years there. And Russia pumps out fossil fuels without any care. They feel that things like opening of the Northern Passage and more agriculture on the previously hardly suitable lands are great for their future (they aren't climate change deniers, they are believers. Like everybody else there, I was taught about climate change as a clearly established scientific fact in the 6th grade in 1985).
So, until somebody brings out 10+ aircraft carriers and enforces global climate accord, i don't see any progress happening here.
I see the major problem isn't that there will be just warmer temperatures, but that the climate will become unpredictably changeable. For the moment, it can be beneficial for agriculture in some areas, but it's likely that our global food production will have to massively change to take into account times of drought and flooding that will destroy crops in some areas. Whereas now we can just grow crops in fields, we may have to grow food in greenhouses just to be able to provide the plants with consistent growing conditions.
There are a lot of variables here, and one is the sun. The other is time.
We can certainly, even without genetic engineering breed crops more suited for shorter growing time frames.
There are a lot of corn hybrids, some mature fast, others far slower. Some require more sun, others less. For example, some of the faster growing varieties only take 60 days to mature, others 100+. But here's the thing. Those are 60 "good weather" days. As in not too much cloud, not too unseasonably cold or warm, reasonable amounts of rain and water, and so on.
As corn takes time to grow and mature, it doesn't matter how much sun you throw at it, it still only grows so fast. Up North, even if it's warmer, you still need enough sun too. Compressing the sun around the summer solstice doesn't help. Giving it 22 hour long days of sun doesn't just magically make the corn grow 2x as fast as an area with 11 hours of usable sun.
And the spring is still "rainy season". Some crops can't take too much rain.
Where I live, a local farmer grows traditional yellow corn, as some prefer it over newer, 'peaches and cream' hybrids. But some years? It just doesn't mature. Too much cloud, or other inclement weather (too hot, too cool, to much sun, etc) and being further north means there is little wiggle room in the growing season.
I guess my point is, Northern areas will require only certain crops. That's fine of course, and it will indeed feed people, but some crops won't be on the table.
One thing that may have already helped Russia, is the extensive work the Soviets put into breeding crops to grow further north:
While I do not doubt the weather is more mild in Russia these days, it's also quite erratic. At least it is here in Canada. Some winters mild, then bam a winter of "old". So I wonder if the above breeds have given Russia a leg up on taking advantage?
Russia exports agricultural products. The productivity has dramatically increased after privatization of agricultural sector and of course they are using those breeds plus some advanced tech sometimes. I have seen a research on how to automate watering during drought in mid-2000s, and that was literally saving the crops. Also the governance is relatively efficient in this sector.
I don't think Russia is unique here. I was talking about it because i know it. i can't talk this way about say China or Argentine (or basically any other country except may be US where 25+ years of residence give me some knowledge to talk about).
So, until somebody brings out 10+ aircraft carriers and enforces global climate accord, i don't see any progress happening here.