Very few things are truly "free" but get paid for by way of some other charges.
I can imagine the anger of someone who has just tied themself into a 30/month mobile contract on the basis that their home broadband was "free" and those people should have a way out of the mobile contract since a significant aspect of their contract has been changed detrimentally.
I expect OFCOM (or similar) will receive a number of complaints about this.
www.thisismoney.co.uk/money/bills/article-2196350/Orange-axes-free-broadband-mobile-customers.html says the broadband will remain free, but switching to Orange for landline service will mean customer pays them about 160 in the first year.
Of course, if someone had been using BT might have paid BT 120 (or whatever they now charge) for a year's line rental at a discount, and will lose any unused months (no refund if you switch from BT).