I think if any junior decides to leave the club they came up through the ranks with, it is going to be for money or because they have been let down by the club (look at Galvin's dissatisfaction with Tigers signings around him).
A player option won't stop that.
It does however give the player the option and security of staying at a pre-agreed price, if they lose form and/or get injured.
Whether the contract is 3+2+whatever or just 3 years only with no options, they will leave if they want to or if they don't get an offer to stay for that they believe they are worth.