I recently sparked a discussion with Furty about this on his stream and we both ended up with the same result. I'm now confident running Chipped Soul Prism + Iron Reaver's Piston is the best route for maximum damage as Destruction. After running some personal sims, I realized that DSI + Fragment actually gives significantly less up front (opener burst) damage than using CSP + Piston.
https://gyazo.com/358f152a6f66f0c9d8f15162a4df5946
These are the results of Furty and I using CSP + Piston on Mythic Archimonde. Zevoa actually has a really strong private parse of Archimonde as Destro with both of these trinkets as well, and I'm sure he will chime in.
The extra stats from both trinkets outweigh any sort of proc based trinket currently available to us. Fragment was a lie all along (it has no stats for e.x. which is all destro is currently looking for) and is actually not strong in the slightest.
Another topic of discussion is the amount of damage loss from having to take a step of movement. This is why Furty, myself, Zevoa and many other top warlocks such as Sparkuggz have ran Supremacy/KJC/Serv to maximize damage punch from having to move.
Sadly, Gahhdo's sims were misleading us the entire time but at least now we are aware of this problem.
Best of luck to all and may the ranks be with you!
Thanks for reading! Enjoy this picture of yours truly!