That's the worst case scenario, which admittedly is the most likely. The value of the chips depends on the rules the casino assigns to them which vary depending on the casino. If they're the type of chips that are kept after a win then their value is near 100%. If they are taken after a win but can be used on any bet then you can raise their value to near 100% by betting on single numbers at roulette. If they are the worst case scenario, taken after a win and restricted to even money bets, I suggest you play craps and try to convince the pit boss to let you take odds with them for the full payout.