Timestream Navigator has a great extra turn ability (Take an extra turn and then put "Timestream Navigator to the bottom of your library"
Sakashima's ability is: You may have Sakashima the Impostor enter the battlefield as a copy of any creature on the battlefield, except its name is Sakashima the Impostor"
If Sakashima comes in as a clone of timestream and activates said ability, would it reamin on the battlefield because its name is not "Timestream Navigator"?
The text "Timestream Navigator" on Timestream Navigator's last ability refers to the object where that text appears, regardless of that object's name (C.R. 201.4; for this scenario especially, see C.R. 201.4b). Thus, if a permanent you control has Timestream Navigator's last ability, whether that permanent's name is Timestream Navigator, Sakashima the Impostor, or some other name, you put that permanent on the bottom of its owner's library as part of paying for that ability (C.R. 602.2, 602.2b, 601.2h; see also Sengir Nosferatu, Urborg Panther [C.R. 108.1], and Trustworthy Scout).
Timestream Navigator has a great extra turn ability (Take an extra turn and then put "Timestream Navigator to the bottom of your library"
Sakashima's ability is: You may have Sakashima the Impostor enter the battlefield as a copy of any creature on the battlefield, except its name is Sakashima the Impostor"
If Sakashima comes in as a clone of timestream and activates said ability, would it reamin on the battlefield because its name is not "Timestream Navigator"?