Is the new event going to end current one?

I know settlers has been up for a long time now but since they said they weren't doing anything on PoE 1, I started a character on the necro event. Will this new event mean and end to the necro one?

No. Events are not Leagues, they take place within a league. It will be like a private league. You can join the event by selecting it in the private league panel below the character selection panel. The same as Necro Settlers. Normal Settlers league will continue until 3.26 is released.

https://www.poewiki.net/wiki/Event for reference

edit: Sorry, can't read. You asked about the end of the Necro event, not about the end of Settlers league. As for that, only GGG can answer that. But my guess is they will announce the end of Necro Settlers at least a couple of weeks in advance. There was no fixed end date when they started the event, so they should definitely avoid ending it on short notice.

It's halfway clear to me that the upcoming event doesn't end Settlers League, because it takes place (as an event) within the League.

What's not so clear is, will the Necro Settlers Event end when the new event launches (or can they afford to run both events simultanously)?
This is what OP is asking for as far as i understand.