From what I can see, it doesn't mean Sky F1 being free-to-air - it is just that Liberty don't like the current deal (that Ecclestone struck) that will put F1 exclusively behind a paywall between 2019-2024. It would appear that Liberty want to maintain something like we have now - Sky show 100% of the races (behind a paywall) but there is also 50% of races on live (and 100% as highlights) shown on free-to-air (e.g. C4 in the UK). The current deal would apparently wipe out that free-to-air coverage, and Liberty are not happy about that (which is good).
Incidentally, Sky are fundamentally reshaping their Sports packages:
http://www.skysports.com/relaunch
Soon each sport will have its own channel (although I notice that the English Premier League will have its own channel over and above 'Sky Football'), so it would be surprising if Sky F1 were to be made free-to-air.