It's not about whether you think you already have the long term option or not. You don't know what could be happening in two years let alone five. You proactively give yourself multiple options - someone might steal someone else's jersey, someone might leave unexpectedly and you need to replace them, etc. Recruit proactively for potential future needs - guys with clear talent & potential - rather than reactively when you lose someone, chasing your tail and overpaying for someone mediocre out of desperation. Example:
Spine players in the 2017 Melbourne Storm squad:
Cameron Smith
Cooper Cronk
Cameron Munster
Billy Slater
Slade Griffin
Brodie Croft
Brandon Smith
Jahrome Hughes
Scott Drinkwater
Jake Turpin
Brodie Croft was thought of as Cooper Cronk's replacement. Jahrome Hughes was the back-up fullback, and he and Scott Drinkwater were seen as fighting it out for the #1 jersey (with Drinks being the more hyped prospect). Brandon Smith hadn't really hit his straps yet but not long after this, everyone would start to assume he'd be the heir apparent to Cam.
In 2018 they lost Cooper Cronk, Jake Turpin and Slade Griffin, and added:
Cooper Johns
Billy Walters
Ryan Papenhuyzen
Harry Grant (upgraded to main squad from u20's)
In 2019 they lost Billy Slater and Scott Drinkwater in midseason after he fell behind Hughes & Papenhyuzen in the pecking order, and added Nicho Hynes. They found spots for both Jahrome Hughes and Ryan P by realising Brodie Croft sucks, and making the big call to drop a grand finalist halfback in like round 21 or whenever it was.
And so it goes after that - Brandon Smith, who half the recruitment managers in the comp were ready to prostitute their wives to if it meant signing him, usurped by an even better player in Harry Grant. A talented guy like Hughes who was always thought of as a fullback, developing into one of the best halfbacks in the NRL, who can probably get himself a million dollar deal for his next contract if he wants.
They didn't call all this in advance. They thought Cheese was their future hooker, Croft the future halfback, and Drinkwater the future fullback. Now all three of those players are gone or leaving, and they're better off for it. Because they bring in players they "don't need" because they "already have their (insert position here) of the future".
Melbourne's genius in running their club isn't that they see things other clubs don't & have this magical ability of identifying diamonds in the rough everyone else misses. Like, I've heard Melbourne's scouts were iffy on signing Papenhuyzen, but Bellyache forced it through literally just because he liked the cut of his jib after having a meeting with him. There's more guessing & luck that goes into identifying talent than people are prepared to admit. Melbourne just literally put more entries into the raffle than other clubs do, and they never think "oh this guy's good: okay then, we're set in this position".