As you have surely read, Destiny 2 Shadowkeep will arrive later than expected and this postponement will also involve some changes to the Wealth Season.
Bungie has in fact published a long post on his official website explaining some of the consequences of returning Shadows from the Deep. The first of these is the arrival of an extra week of Iron Banner, whose return will give the Guardians a fourth and final chance to complete Lord Saladin’s feat and get the entire set this season. The other novelty concerns the extension of the Moments of Triumph, which will now end next September 17, 2019, and not August 27th. There is no news of a possible increase in the duration of the Solstice of Heroes, a timed event that, with a few more days, could give players the opportunity to forge the first sets of armor that with Shadowkeep will acquire the new perks.
Obviously, all these changes will also have an impact on the duration of the seasons of Year 3, which could last less than usual. It is not clear therefore if Bungie will start the third year of the game with a shorter season than expected or if he will decide to start the Year 4 (or the launch of Destiny 3) just on October 1st, 2020, in order to guarantee seasons of the usual duration.