Trademarks and patents can be tricky. When you trademark a phrase, or particular form of font (think of the COORS cursive written word) you are trademarking an item according to its specific catagory. Also, it can be tied into brand recognition.
For example- Suppose a person wanted to use the same font as the COORS company uses to write the name of their business on banner (but their business is strictly auto related), while Coors CAN complain, and even attempt legal action, because they are in a different catagory of goods, COORS cannot stop the other guy.
Or suppose you invented a new pot scrubber and wanted to call it "The Cadillac Pot Scrubber". The Cadillac car company would have a hard time stopping you (provided you have the money to fight them back) from using their trademarked name, since you are in a totally different catagory of goods.
There are ALOT of hoops and loopholes when it comes to patents and trademarks and registered trademarks. Patent law runs very different from regular law.
Subway may be attempting to stop others from using the "foot long" words in a catagory specific way, but I highly doubt they will be granted it. Like previously stated, it is more of a public domain thing, and it has already been used in commerc for too long.
As to the donald trump thing- His trademark stuff is 2-fold, he trademarked it since it was part of a catagory specific turn of phrase as part of his personally owned show, and 2, he has too much pull because of his money. Us regular Joes are NOT infringing on his trademark by using the phrase, but should we happen to go onto a reality show and use the phrase, THEN we would face litigation (if we did not have his prior consent).
I think this Subway thing is really STUPID. The United States Patent and Trademark Office is already backlogged by several years, the last thing genuine patent applicants need is stupid applications gumming up the works even more.
I'm pretty sure my info is fairly accurate, my hubby and I have over 15 patents and work in the patent and trademark world. If anyone should happen to know if I mis-spoke, please feel free to correct me.