May is taking a huge electoral risk with those social care provisions, they are bound to lose her seats she could have won. However social care is a huge cost and can't be financed as it is. I don't think Labour have any concrete policy on this, they just say they'll reintegrate social care with the NHS, repeal the Health and Social Care Act and 'properly' fund the NHS.
If you rent or are in social housing and virtually no savings you'll pay nothing, its only people owning houses that will pay. As it stands you can pay if you live a long time but you may.
In my own experience I had one Aunt who lived into her 90's spending 4 years in a home who left very little and another Aunt who lived to a similar age but ended up spending her last 2 years in the NHS system after breaking her hip, she was never well enough to go home but bounced between hospital and several care facilities, the value of her house remained in her estate but had to be sold in case care costs were needed. So it is a bit of a lottery even now.
So what happens, will insurance schemes spring up or will home owners gift their homes to their offspring provided they can live there till they die (gifts are not liable for tax if the gift giver survives another 7 years) . There will be avoidance schemes for sure but in the end I feel sure some sort of compromise will emerge though there won't be any back tracking till after the election.