Today is the "12th day prior to the start of the regular season", which means that the waiver period has officially begun. As reported this afternoon, the Flyers have requested waivers for the following players in the hopes of reassigning them if they clear: Johan Backlund, Jason Bacashihua, Jon Kalinski, Stefan Legein, and Dan Jancevski.
So if we need any of these guys in the future, which ones need to clear re-entry waivers to return to the NHL?Only one: Johan Backlund.
Re-entry waivers are a different breed from regular waivers, which are those requested before reassigning a player to another league. When a player is placed on re-entry waivers, if they are claimed by another NHL team the Flyers would be forced to pay half of the player's remaining salary and carry 50% of their cap hit for the remainder of the contract. While you can't be eligible for re-entry waivers unless you are first eligible for regular waivers, re-entry waivers have their own requirements. The full explanation is a topic for a different day, but here's the information that matters for the 5 players waived today.
For one thing, a player must have an AHL Paragraph 1 Salary greater than $105,000 dollars to require re-entry waivers. This means that Jon Kalinski and Stefan Legein do not have to go through the re-entry process. There is also an exemption for Veteran Minor League Players, who have played hundreds of games in North America but haven't spent significant time on an NHL roster during the past two seasons. This exemption covers both Dan Jancevski and Jason Bachashihua, as they exceed the requirements by a large margin. Those four players can be freely recalled at any time, if needed, as documented in Section 50.9.(g).
That leaves us with Johan Backlund. Due to his one way contract and only being in North America for a few years, he'd need to clear re-entry waivers if called up under non-emergency circumstances, and the Flyers would take the risk of him being picked up by another team for half price.
That doesn't guarantee that he'll never be seen in a Flyers uniform again, as his salary is small enough that he may be worth the risk. It does, however, make it a lot less likely.