It appears as if there are variant translations of Luke 16:16 as well.
The international Standard Version offers this understanding
[/i]"The Law and the Prophets remain until John. Since then, the good news about the kingdom of God has been proclaimed, and everyone entering it is under attack.
To be honest, I don't see how this translation can be justified, specifically where this "entering" is coming from.
Going back to the text in Matthew we see a couple possibilities.
The verb βιαζεται and the Noun βιαστα as a form could be understood two ways. The text can be understood as a middle or as a passive form.If it is Middle then we would most likely understand it as entering forcefully which seems to be you position. On the other hand we also see the passive which would suggest that they would suffer violence as they entered in.
I'm not sure what you mean. In the Matthew verse, ἡ βασιλεία τῶν οὐρανῶν is the subject of βιάζεται so as far as I can see either it is coming on forcefully or suffering violence, not the people entering it (at least not explicitly in the text). There is another possibility that I forgot to mention, though -- some commentators seem to take βιάζεται here as passive but as meaning "grabbed with force", so then the two parts of the sentence would be roughly parallel: the kingdom of heaven is seized by force and the forceful gain possession of it.
I'd also point to verse 15 ὁ ἔχων ὧτα ἀκουέτω which usually seems to indicate that something is being said in a particularly strange or forceful way. That's another reason I read it not as referring to some kind of actual violence against the kingdom of heaven (which doesn't seem to fit the context anyway) but about being strong in faith, especially with the contrast to the people who wear soft clothes a few verses earlier and the severity of John's faith, but him still being less than the least in the kingdom of heaven.