I don't think they will EVER go out of style. They are still going strong since their conception as can be seen from the daily posts on this forum with many debating which one to purchase next.
When I decided I wanted to buy a bracelet, I looked at all the upscale brands and styles. My husband and I looked at the equivalent priced bracelet at Tiffany's, and I am so glad I did not go for it when my husband was all set to purchase it with a very eager SA there to back him up! It just didn't feel substantial or right for me nor did it justify the price. When we finally were able to get to the Cartier store (as I don't have one in my city), I knew right away I made the right decision in waiting.
The Cartier Love is unsurpassed in my opinion in terms of craftsmanship, weight, classic & modern/sleek look, timelessness, comfort (I could go on), and once you purchase one, you will want another because you will LOVE it so much (no pun intended)!
Quite honestly, I hate being trendy or having something that screams label on it, and luckily, the Love really is not very label-ly & rather discreet since it's not screaming Cartier unless of course, you recognize its motif, but because of everything I stated above, I had to have it! There's nothing else quite as well-made and aesthetically pleasing as the Love!