We can’t say for sure Luke is dead when Episode IX might turn that scene on it’s head. After all, the mechanical hand didn’t vanish. 😉
Exterior: Space
Pan down to Ahch-To, First Jedi Temple at dusk.
LUKE’S mechanical hand appears, floating for a moment over the discarded cloak.
A Porg lands on the cloak, and the hand comes alive, brushing it away and snatching up the fabric, which disappears into thin air.
Interior: Lando’s Sail Barge
LUKE appears, hastily adjusting his cloak, before Rey.
REY: (Jumping up from her seat) You came out of nowhere!
LUKE: That makes two of us.