As the summer heats up, blockchain hype may (finally) be cooling down.

2016 will likely see less investment in bitcoin and blockchain technology, but that is true for many other areas, as well. This year to date has seen $161 million invested so far, while 2015 saw a total of $488 million, according to the investment tracking site WeUseCoins. That means investment in bitcoin and blockchain technology is on pace to total $309 million this year, down about 37%.

The reason for the slowdown — dramatically displayed at right by Google Trends — is not only our human inclination to look for the next big thing, but also a growing sense that blockchain implementation in financial services will be a marathon, not a sprint.

An early bucket of cold water came in April from Gideon Greenspan, CEO of Coin Sciences, which builds private blockchains for companies. Greenspan took issue with the hype about smart contracts, a specialty of Ethereum, best known now for its hack and the current hard fork debate.

Smart contracts simply cannot accomplish many of the use cases attributed to them, Greenspan argued. His first example was contacting outside services:

Often, the first use case proposed is a smart contract that changes its behavior in response to some external event. For example, an agricultural insurance policy which pays out conditionally based on the quantity of rainfall in a given month.

The imagined process goes something like this: The smart contract waits until the predetermined time, retrieves the weather report from an external service and behaves appropriately based on the data received.

This all sounds simple enough, but it’s also impossible. Why? Because a blockchain is a consensus-based system, meaning that it only works if every node reaches an identical state after processing every transaction and block.

Everything that takes place on a blockchain must be completely deterministic, with no possible way for differences to creep in. The moment that two honest nodes disagree about the chain’s state, the entire system becomes worthless.

He goes on to show why several other uses of smart contracts will probably not be possible. A few months later, Ethereum was hacked and millions of dollars worth of its proprietary currency were stolen. They can be retrieved, but in a way that may compromise the integrity of the entire system.

While Greenspan’s examples are quite specific, more generally the investment temperature seems to have dropped a bit around distributed ledgers in the financial services sector. A June report from James Wester, research director for worldwide payment strategies at IDC Financial Insights, explains why.

“The disruption facing networks and platforms is likely to be gradual,” Wester writes. “Thus, for financial institutions, vendors, networks, and others in the payment value chain, the concern now is how to begin understanding blockchain and distributed ledger technology. Before that can be addressed, however, there are significant issues blockchain technology must overcome.”

Put briefly, banks don’t do anything quickly, and blockchain technology is still developing, with significant challenges yet to overcome.

Wester, for his part, is bullish on the consortia of banks, going as far as to compare them to the card networks: “It is through these consortiums [sic] that the technology and processes will evolve, potentially even supplying the infrastructure over which applications are built. It would be analogous to the initial development of MasterCard and Visa as nonprofit rule-making associations of cooperating banks. It was through their efforts to establish secure, reliable, rule-based payment networks that saw the rapid rise of credit and debit cards over the past few decades.”

As the hype cools, perhaps the real work can begin.