Senior executives at United Airlines (UA) and logistics giant UPS think 2019 will not be the year blockchain goes mainstream, the Wall Street Journal reported on Dec. 28.

Speaking to the publication, UPS chief engineering and information officer Juan Perez and UA’s executive vice president of technology and chief digital officer Linda Jojo remained level-headed on blockchain’s prospects.

“We have a small team looking at blockchain, but we are still searching for the killer use case,” Jojo said.

As 2018 draws to a close, blockchain has faced mixed reviews in the press and from businesses, some sources claiming the technology is not developed enough to fulfil its disruptive and even innovative promises.

By contrast, the year began with companies seeing huge share price increases simply by adding the term “blockchain” to their name.

Gauging genuine interest from the international community has been difficult, with a survey by India’s Tata Communications this month nonetheless revealing a 44 percent uptake rate for blockchain across international respondents.

Governments also continue to signal their desire to get a hold on the phenomenon, with Italy this week publishing a list of 30 “high-level experts” who will help develop an official state strategy.

For UPS, however, it is still too soon for real implementation.

“I don’t expect significant benefits in 2019, primarily because the technology itself is continuing to evolve and mature,” Perez continued, adding:

“It requires a lot of parties to come to the table to participate and evaluate the technology.”

In August, the company had issued a blockchain-related patent for the logistics industry.