When a new expansion appears for a game like Destiny, there is a reasonable expectation that the large amount of new material thrown into the game will confuse your load. And yet, players always like to carry their favorites too. A problem with Destiny 2 The expansion of Forsaken now seems pretty obvious, even if it slipped below the radar at that time. Because of the changes that are being made to legendary weapons and armor, almost all your legendary weapons and armor will be, if not useless, at least far less useful than anything new you find, and that includes things like Solstice armor.
Cheap Destiny 2 Boosting now have a second important advantage as part of the new random roll system. Current weapons only have one. The armor will now also have a benefit, while the current armor has none, only mobility / resilience / recovery modifiers. So, the point is that even the weapons that you like now, Midnight without a name, Better Devils, whatever, will probably be surpassed by other weapons immediately since each new fall has an extra benefit now.
And any piece of armor with an advantage will automatically be better than any armor without one, which means that all the legendary armor you have today is nothing more than cosmetic. This is obviously a positive change, but it means that your vault is now filled with a lot of hot garbage. While Bungie has not said it openly, it seems almost certain that there is no way to just retroactively add new advantages to everything you have now to make up for this. They said they were not going to randomly fire your current weapons, so the implication is that they will not, randomly assign everything you have new advantages to.
The only exception here is probably exotic. I do not think that the exotics of the Forsaken era receive an extra bonus in all of them, and all of them have fixed advantages to start with, which does not change. So your exotic collection is still going to be useful in the future, so that's nothing, I suppose. The solstice armor of the heroes is useless, it's a bit annoying and dampens my enthusiasm for a bit, but if I'm totally honest, it was always pretty much an achievement for the sake of achievement. 400 power does not really matter in the current state of Destiny 2, and when Forsaken comes, with the limit increased to 600, it was always going to be overcome immediately. And again, if this is the price we have to pay to give the armor real benefits again, in the end Destiny 2 Boosting is worth it.