The only evidence there is would be history It that would be like saying it took the first ipod took 15 years to create so ipod 2 will be here in another 15 or 20 years. Evidence would say each generation of any manufactured product will be faster and better till "a maximum effectiveness" (Highest bang for your buck) is achieved.
I couldn't begin to guess how far off the "maximum effectiveness" for spider silk would be.
EDIT to your next statement Mike.
You really think that was what he meant? I took it to say MS was being tested
"It's", is what he is speaking of in the line before.