Quoted from jackd104:Assume 7 is the max number. The current scheme brewing in my brain is to replace TZ, TSPP, & NGG. I love these games but had them a long time.
the best thing is that if you miss any of those games, you will be able to find them again
I'd put all three up for sale, sell one or two and keep the last one. Then buy one new game and see how your collection feels