Many artists never see the full peak of their career because it happens after their death. Vincent Van Gogh barely made a dime off of any of his paintings during his life. His paintings now sell for millions. While, the comparison to a country song is a bit extreme, it goes to show that death sells. Nirvana and Sublime both saw increases in sales after their lead singer died. The same can be expected for Tim Wilson.
The song will grow in stature because of the death of Tim Wilson. His Nascar song had been doing alright but now because of the attention his death has received, his song will be requested to play more often now. People will also want to download the song more than ever.
I think that the death of Tim Wilson will make his NASCAR Song. People always will resort to embracing a product or song just because it has garnered some attention. And somebody dying is usually something that will get something like a song more attention. People will also make it more popular for novelty purposes.
Tim Wilson will always be remembered by his fans, but with his passing, in the immediate future, I don't think his NASCAR Son will be more popular. It may receive more plays given the fact that people tend to memorialize people, but I don't think that will have lasting implications in this case.
I don't think that the death of Tim Wilson will make his NASCAR Song any more popular than it already is. For example, I had no idea who Tim Wilson was or that he had a song until I researched for this question. All the people into NASCAR already know about it. Those who don't, simply do not care.