The specifics aren't clear yet. I know my main source is a few months old, but to my knowledge, no specific plans have been presented yet.
Plans to decriminalize not paying the license fee are looked at, according to then chief secretary to the Treasury and confirmed by the PM's office. According to the Guardian (dated 15 December 2019):
Even more worrying for the public broadcaster are comments by chief secretary to the Treasury Rishi Sunak, confirming plans to look at the decriminalisation of failing to pay the TV licence, which could be set out in the next Queen’s speech and would undermine the BBC’s funding model.
Sunak told the BBC’s Andrew Marr Show: “That is something the prime minister has said we will look at, and has instructed people to look at that. I think it’s fair to say people find the criminalisation of non-payment of the licence fee to be something that has provoked questions in the past.”
A No 10 source confirmed that the licence fee was “in the firing line”, following reports in the Mail on Sunday that its future settlement was under discussion.
The specifics aren't known yet because the government is still looking in to their options, from the same article by the Guardian:
A BBC spokesperson said decriminalisation would lead to £200m less to spend on programmes.
“The government has already commissioned a QC to take an in-depth look at this matter and he found that ‘the current system of criminal deterrence and prosecution should be maintained’ and that it is fair and value for money to licence fee payers,” they said. “Decriminalisation could also mean we have at least £200m less to spend on programmes and services our audiences love.”
There is a more recent article by the Guardian entitled BBC licence fee: proposals to decriminalise non-payment but I don't see any concrete plans mentioned there. The culture secretary is quoted casting doubt once more on the future of the license fee:
The culture secretary, Nicky Morgan, said that “the time has come to think carefully about how we make sure the TV licence fee remains relevant in this changing media landscape.”
She added: “Many people consider it wrong that you can be imprisoned for not paying for your TV licence and that its enforcement punishes the vulnerable.”