It's official, I'm now the only senior in my team, the other person got promoted for a new position in a new team and now I'm fucked.

I am the only senior in my team as well now, After some re-org in the company I work for, it turned out that way.

I look at this positively, I have taken this title and lavraged my salary.
Also, I like having a "say" in all sorts of design stuff.

I guess if you see you are overwhelmed by the responsibilities or that everyone comes to you with questions too often,
I would suggest to put your effort on creating some good documentation and pointing people there.

@noyloy There is already good documentation created but the truth is people don't have the skill to do what I do therefore I am loaded all the time while they do menial tasks.