Are some of the items from perandus staying in the game?

Tought i am mostly asking for varanustra i'd like to know if there is a place where we can know if some stays?

Varunastra is exclusive to the Perandus league.
It stays in the game but won't drop any longer (there could be exceptions like Zana's league mods).

You can see which items are: http://pathofexile.gamepedia.com/Perandus_league

I think, but I'm not sure, you can also nab League Exclusive stuff from the generic Divination Cards.

So if there's one that gives out a Random Unique, or a Unique Sword, you can nab a Varu.

I may be wrong though, honestly.

Varanustra, Umbilicus and Trypanon were really cool build-enabling uniques, I hope they stick around in some form or other.
(Zerphi's last breath also enabled one really cool build; but there's not many builds it can work well with.)

Perandus manor probably should stay league-only.

Seven-League Step was stupid.

All the perandus league items were common grade drops, worth ~1chaos for most of them so there will be hundreds, maybe thousands that flood into standard.

That is, if people didn't vendor them.