Let's say for hypothetical reasons I want to trademark T-PST (short for toothpaste). I want to call my toothpaste business T-pst. Another toothpaste company is using the name TpasteCo, and yet another is using the Pst. We all manufacture toothpaste. If my company takes off in 5 years do you think the other two companies can sue me in the future for trademark infringement?
(this is a hypothetical name and business but is close to a situation at hand - I can't think of a better example).

