Littleton Chambers provide an interesting summary
https://littletonchambers.com/commentary-on-todays-supreme-court-decision-in-uber-bv-v-aslam-and-ors/
Quotes are from the judgement, selected by Littleton. The commentary is mine - and I'm not a lawyer.
".... it can immediately be seen that it would be inconsistent with the purpose of this legislation to treat the terms of a written contract as the starting point in determining whether an individual falls within the definition of a “worker”. To do so would reinstate the mischief which the legislation was enacted to prevent."
The "legislation" is the various employee/worker protection legislation. The Supremes are basically saying that the law comes first and you can't use weasel words to get round it. Actions define the relationship, not the contract. They also said:
".... any terms which purport to classify the parties’ legal relationship or to exclude or limit statutory protections by preventing the contract from being interpreted as a contract of employment or other worker’s contract are of no effect and must be disregarded.”
So it would appear that Uber lawyers can't really get round this just by adjusting the contract. The court also said
" although the drivers were free to choose when and where they worked it was the case that, at times when they were working drivers, they were in fact workers for and under contracts with Uber London"
This is not based on the contractual definitions, but on the amount of control they had over the work they did - the driving - not the choice to drive or not.
So it would appear to me that Uber's only way to get round this is to give drivers much more control over their work when they are actually driving.
IANAL, but the Supremes seem to have come at this from a direction that makes it very hard for Uber to weasel out of it without making significant changes to the way it works. The approach (how does the law apply to what they actually do, not what they signed up to contractually) seems to be tailor made to go after some other elements of the gig economy too. Littleton's closing comment in their review of the case is:
"In allowing the appeal the Supreme Court has however made largely redundant “armies of lawyers”."