I think in terms of any legal consequence, it's at least plausible that anyone involved in the operation of the Patreon could be taken to court if they never release an update.
If someone promises a specific product, reach their funding goal, and fail to deliver the product, they could face a breach of contract claim. For that reason, they need to be very careful in determining what rewards they plan to offer. Failure to deliver or delivering a sub-par product that doesn’t live up to the promised description can bring a claim from the funders for breach of contract, either on an individual basis or as a larger class action.
Overpromising or overstating what they are offering can open them up to more than just a breach of contract claim if they fail to deliver. It can also expose them to claims under consumer protection laws, false advertising laws, or claims under common law such as fraud or negligent misrepresentation, on the theory that they convinced people to give them money by misstating what they’d receive in return.