I'm not totally clear with how it works, but I think he's still waiver exempt, just technically. Sami signed his ELC two days before his 20th birthday, so that makes him waiver exempt for four years from that date, not three, meaning he's still waiver exempt for another year. And, since he's only played in 56 games, he hasn't reached the 60 games threshold for a 23 year old, meaning from that criteria, he's still waiver exempt. Although, another blog says it's the age the player reaches that calendar year, which, if that's the case, Sami's not exempt from waivers after this year.
It's a moot point, anyway. I highly doubt he signs another two-way deal, and I highly doubt the team tries to send him down anyway. I believe he's here to stay, and unless he's traded in a bigger deal, they'll move other guys to accommodate him. BB appears to have faith in him, and I won't be surprised to see him called up and inserted into Robidas' spot(although I won't be surprised if he isn't, either).