Smith is scheduled to make $2M next season and at 40 years old, it was unlikely he was going to return. The Oilers are planning to place Smith on LTIR for the next season freeing up $2M in cap space. This is similar to what the Leafs have done numerous times in the past by sending players to what Leaf fans call "Robidas Island". Chris Pronger also "retired" from the NHL but didn't file his papers until his contract expired.
With Smith headed to LTIR, the goaltending search has likely already started. There has been plenty of speculation that the Oilers could be looking at Jack Campbell as their new number one if the Leafs don't re-up the 30-year-old netminder. Another possibility exists as well, where the Oilers could trade for Campbell's negotiating rights if they want to get cracking on a new deal early, but as we saw last year with the Zach Hyman debacle, Ken Holland is not exactly the most reasonable guy when it comes to parting with a fair value piece, such as a draft pick, in exchange for a player's rights. Last year, it cost him the 8th year and an extra $500K per season on Hyman last summer.
Smith was instrumental in the Oilers' run to the Western Conference Final, albeit having a few horrible performances along the way. He stepped up when the team needed him most and helped the Oilers make the third round for the first time in the Connor McDavid era.