btc itself could be patent by anyone just because it's public by nature, it was created with this purpose.
We have developers who have already replicated the bitcoin blockchain. There are so many altcoins that are clones of bitcoins, it will run a lot of altcoins out of business if we have a bitcoin patent.
Yes this is absolutely true but there is any real "trademark" behind btc and probably we'll see another "blockchain" patented and not this one
Nothing that has already been demonstrated in public can be patented, so after the Bitcoin code was published on Sourceforge and Satoshi had started mining the blockchain it was too late for anyone to patent it.
Anyone can file a patent that uses Bitcoin in some new invention, but the patent office might not necessarily accept it.
I searched the US patent office for Bitcoin, and there were 109 results today. If anyone wants to have a look at them put Bitcoin into the search box on this page at the US patent office.
http://patft.uspto.gov/netahtml/PTO/search-bool.html