'only became possible' is correct and usable in written English.
You can use it to describe something that has recently become achievable or available in a particular context. For example, "The introduction of new legislation only became possible after a long campaign led by the pressure group."
For his thesis, he constructed a neutron generator, and originally intended to discuss the possibilities of studying neutron diffraction in crystals, but this really only became possible with the development of nuclear reactors that produced large quantities of high energy neutrons.
The exploitation of the samarium neodymium pair for dating only became possible when several technical difficulties were overcome.
Black's central argument is that the romanticization of the Yellowstone wilderness only became possible after the extermination of the indigenous population.
The desire to collect only became possible about 12,000 years ago, once our ancestors gave up their nomadic lifestyles and settled down in one location.
"It began in 1997, but it only became possible to build it during the financial crisis – when the contractors were cheap enough to do it".
As Karavkin says, it only became possible by "some miracle" – laws set such strict standards that self-assembly cars would not usually meet them.
The main decisions of international institutions only become possible when nation states agree.
When they emerge, as was the case with President Anwar el-Sadat of Egypt and King Hussein of Jordan, peace not only becomes possible, but also inevitable.
Ralph Kundig, one of the lead campaigners, said ahead of the vote: "For centuries this has been considered a utopia, but today it has not only become possible, but indispensible".
Back then, the popular approach wasn't deep learning, a method which has only become possible as processing power, storage space and, yes, data availability have all come of age.
Such creativity only becomes possible if both the necessity and the desirability of higher fuel taxes are patiently but robustly presented by Tony Blair, Gordon Brown, John Prescott and all the rest of the pale green Government.
