Approximately: How much will a autographed picture by Kyle Busch(winning at Darlington) be worth in 20,30 yr?

It's impossible to say. It depends on what kind of career Kyle Busch has. Also, memorabilia values can fluctuate, but it should never lose value. Is it mint condition? Do you have a COA? If you don't have a certificate of authenticity, I would urge you to get one, but from a reputable source. You may have to pay a little more than you would for a fake one, but it's an investment.