I think we are talking about two different things here.
Bitcoin can't be banned as a technology because you can't prevent people for using it, it's available for everyone. But the other thing is that governments could put the use of Bitcoin out of the law so that it becomes illegal. So, basicly you could always use Bitcoin because all technologies, sofwares and devices are available to you but you will be doing it on illegal way if some governments adopts the law against Bitcoin.
To my opinion there is no fear of banning Bitcoin because most governments, at least in developed countries, are aware that Bitcoin and cryptocurrencies can't be marginalized anymore.
Thanks for the objective outlook with regard as to if or not bitcoin will be banned, Government regulations and alternative factors can certainly increase as bitcoin becomes more widespread, cryptocurrencies are presently in a very well legal status within the US. Countries like Japan have embraced crypto greatly - it's going to be interesting to see the market effects of countries increasing regulation, however as of currently I do believe the notion that it cannot be stopped.