The announcement came in the World of Warcraft Dragonflight expansion reveal stream, which made sense, given the dragon-themed tie-in. Yet, the release of the second WoW expansion is making it to Classic this year, and will increase the level cap and bring the continent of Northrend into the fold. The addition will also bring in the Death Knight at level 55. When the expansion launches, the cap will rise to 80 but Blizzard will be providing everyone a level 70 boost that they can use on any character, but this also includes the Death Knight.
You'll be able to make your first Death Knight without any restrictions are having to complete any prerequisites first. You also have the new inscription profession available that will let you scribe glyphs to alter abilities and spells, as well as adding the ability to craft trinkets and off hand items.
Achievements will be coming too, so this will change the reward system to add some extra for players who devote their time to Classic. For subscribers, the expansion will be added for free and there will be some additions, including the original barber shop that was introduced in the original release as a paid feature, this time will be added as a free feature that you can spend gold on in game to use.
Something that players might welcome is the ability to take on 5 player dungeons without needing to use the automated Dungeon Finder. Sometimes, especially if you are a dedicated Classic player, you want to go in there with a team you know you can count on and not leave it up to chance with a random recruit.