There is print talking about the limits. The batches of rewards may also be refilled, depending on the contract/promo deal.
The rewards are in batches. The company running the promotion will have a contract with the game company. The game company issues batches of codes based on that contract. So, if they ask Blizzard for more codes then depending on the contract, Blizz might give them more.
During the Promotion Period, reward items will be available in limited numbers, and are available while supplies last and are subject to availability (“Rewards”). To explore the available Rewards in the marketplace (“Marketplace”), visit the Website. Participant will only be eligible to redeem for Rewards for which Participant has banked enough Points for. To redeem for a Reward, the Participant must navigate to the Reward and select their choice, then click, or tap the Redeem Now button to redeem that Reward. Participant will receive an email confirming the Reward they redeemed, and the Participant’s Account will be debited the corresponding number of Points after redeeming a Reward. Participant will also be eligible to redeem 100 Points for a Sweepstakes entry (“Sweepstakes Entry”) during each Sweepstakes Entry Period. Participant will receive an email confirming they received a Sweepstakes Entry and the Participant’s Account will be debited by 100 Points. There is no limit on the number of Sweepstakes Entries a Participant can redeem Points for each Sweepstakes Entry Period assuming Participant has sufficient Points in their Account.
All Rewards available on the Website are subject to change without notice. A limited quantity of physical Rewards will be released each week during the Promotion Period. Check back regularly each week. Rewards will be redeemed on a “first come, first serve” basis in relation to when Participants electronically complete “check out” transactions in their Accounts. Once supplies of a Reward offered are exhausted, the Reward will be shown as out of stock.
Once any Reward is “out of stock” that Reward will no longer be available, unless restocked, as determined by Sponsor, in its sole discretion. Restocking of any specific Reward does not indicate that further restocking of any other Reward will occur. No exchanges, returns or refunds on any Rewards are permitted for any reason. Sponsor may, in its discretion, add new merchandise for redemption during the Promotion Period.
https://www.mtndewgaming.com/terms-and-conditions
Hopefully Blizz gives them more codes for folks to redeem, which the promotion company will need to ask for. It would be logical that Blizzard would provide them more codes given how long the promo runs.