That is what they want, but that isn't something they can get. A 100 horsepower tractor will be expected to deliver 100 horsepower for 15 hours without stopping (it is common to eat while driving, though you will stop for a bathroom break here and there). That means you need to have a 100 horsepower engine. Contrast a Tesla which is rated at 600 horsepower - but realistically only can give you that for a few seconds before you are at speed and then only needs to deliver about 20 horsepower. The batteries in a Tesla would run that 100 horsepower tractor for maybe an hour, so a 20 horsepower engine in a Tesla could easially extend you a lot of range.
I work for John Deere. I don't speak for the company. I can tell you that we are looking at electric for small tractors - there are a lot of people who only use small tractors for a couple hours per day (or less). We have hybrid tractors for some applications, but there are others that hybird isn't useful. The rules of chemistry tell us that a battery will never be useful for large tractors, and even small tractors it is questionable if batteries can ever be good enough to go all day (if you look at our electric mower the dealer is required to examine your lot to make sure it isn't too big). We have tried things like put a 1km cord on a tractor - I don't know what the status of that is.