Having looked at the judgement and some of the wider analysis, I'm not entirely sure why everyone is getting so excited. Nothing is going to change in the short term and for any change to stick the law needs to be changed. Firms 'engaging contractors' can just modify their terms and conditions to get around it, at little cost to them. The 'contractors' can't do anything about it if they want to continue getting the work.
If you read Ubers statement, (which I'm inclined to give stock to) it's their view judgement is likely to only impact the few people who bought the case and it reflects their time on the service only. Uber says it has changed the arrangements with its drivers since so this case may not actually be binding and I don't think there is nothing from stopping them changing them further to make it further irrelevant.
The ruling also fails to take into account how the market has changed over the last few years, particularly with drivers drive for 3 or 4 apps at once. I think what this does do though is show that there are serious issues with employment law in the UK, the definition of a 'worker' is different in different bits of legislation. It's old, clunky and no longer fit for purpose in the modern world.
There are so many 'self employed contractors' with far less control than Uber. Look at the big courier firms for example, you 'buy a franchise' for £400 and you are then forced to rent one of their vans, wear their uniform, use their equipment, turn up when they say so, deliver when, where and how they say to. They give you training to do the job effectively, other than having to pay for access to the work, it sounds awfully like an employer-employee relationship. You literally have zero control.