Other possibilities are adding the licence fee to council tax or electricity bills.
The situation is complicated by the way in which the BBC also offers radio stations and a website which are 'free' to use - as in a TV licence is not required to use them.
That only complicates an equipment licence - which other European countries are moving away from. If you move to a 'public service' funding model the accepts the public value of a PSB then that's not a major issue.
As I have mentioned in previous posts, there are questions as to exactly what should and should not be considered as PSB, and whether it would make sense to move most stuff which is not PSB material that can probably survive in a commercial environment to a commercial division of the BBC funded by subscription, leaving the PSB division funded by whatever replaces the TV licence.
I think that's a route to PSB ghetto, which would potentially mean the public services provided were only those the market did not. That would be a recipe for disaster, and the public - and then politicians - would probably question the value of the core public service.
If you only did Newsnight and didn't do Top Gear, only did Sunday Politics and didn't do Strictly - you'd have a lot of people asking questions...
Plus commercial funding would cannibalise the advertising revenue for other public service broadcasters - ITV, C4 and C5.
A hybrid funding model is probably the best solution.
Not everyone agrees. I think both the German and Swedish models have some merit - and both were triggered by an acceptance that general public service broadcasters (not narrow 'what the market doesn't provide') are good for national life, and that access to services is on so many devices, it makes no sense to tie payment for them to a single device type.