Hang on a minute.
If insurance means anything, it means insuring against known risks. So age, sex, driving history, address, type of job, type of car etc all create a risk profile for a given driver.
Now that the sex of the driver has been taken out of the equation, other information should become more relevant.
This may all shake down so women may still pay lower premiums if the other factors put them in a lower category.
Eg - better driving history (because, hey, they have fewer bad accidents); driving less powerful cars (possibly a financial decision, possibly my sexist assumption); they live in safer areas (ok, this is unlikely, but may be that women seek out "safer" areas with less crime if this is achoice); job (perhaps more women tend to have "safer" jobs - again my sexist assumption); age (do they start to learn to drive on average a few years later than me?)
Insurance is a competitive busines, and insurers will still be looking to make the very best assessments of risk, and it may be, given my examples above, that women will still, on average, get lower premiums than men.
We can but hope.