You are right... an improved "anti-plagiarism software" will result in advances in "plagiarism-detection-avoidance". It's sort of like a "cold-war" between teachers and students.

I was watching one of those "TV-exposes" on "Buying term papers", and I can just see them selling "plagiarism-detection insurance" as an extra add-on cost. :-)

Plus its a better business to be in.....there are always a fresh supply of "student-customers", but a limited market of teachers. ;-)