Such a move looks awfully like a classic example of predatory pricing to me: make it free, wait until every one uses it and all the free alternatives have gone, and then start charging. After all, it costs nothing to make a function call, which is all an autoshare is.
I find myself looking very warily at Jetpack now, and I may simply deinstall it.
In the meantime, does anybody have a recommended autosharing plugin for Twitter?