Vaulted content - What's affected?

This subject may already have been covered, but I couldn't find exactly what I was looking for. My main question here is, 'Will any of the Forsaken DLC be affected by the vaulting? and if I haven't started the DLC at present, will I still be able to obtain all the achievements after the move has been made. Thank you in advance.

Here's Bungie's post about what is staying and what's going.

https://www.bungie.net/en/Explore/Detail/News/49454

Achievement wise, the only thing that will no longer be obtainable are the two related to the Leviathan raid in the base game. Others may become more difficult, but those two (beat Leviathan, beat Leviathan in Prestige) are the only ones that will not be possible. Of course, it's always possible they change the reqs and just make you beat any raid instead of Leviathan.

Can anyone elaborate on what Triumph Seals would available and best to do after the 10th November? Is the Wayfarer possible from this moment in time?

Flashpoint, Exotic Achievements. All DLC Forsaken achievements, but not for seals, collection card, Gambit or Triumph

The only seals (that can be used for this achievement) that will be available after vaulting will be Dredgen (Gambit), Unbroken (Crucible), Cursebreaker (Dreaming City), and Rivensbane (Last Wish Raid). The others are being vaulted.

https://www.bungie.net/en/Help/Article/49070