You asked about "Modern day classic Rolex" and not "collectible"
hypeIncreasing value and collectibility (is there such a word?) is determined by the market and seldom by the watch itself. Sorry, I'm not a collector or vintage specialist. With the number of Submariner(s) and GMT(s) being produced by Rolex, what more with it's new factory and their long production years, I doubt any of them will appreciate greatly in value.
Furthermore, asking prices and actual selling prices on collectibles can vary so much that you'd be so happy with a purchase until it's time to sell... and then it's like

Lastly, never think about making money with watches unless you're going to buy and keep for 20 years and resell. Then maybe you can get a good return, but only without taking inflation into consideration.
Now buying rare Pateks, that's a different story.....