The problem that American Politics has is not the two party system, but rather the personalities and behavior of people. Attendance at TEA Party functions continues to display arrogant individuals who want only have political influence and use that particular platform; hence the ineffectiveness of a third party.
By that logic all parties are ineffective.
A Tea Party convention will have a certain influence on the GOPe. It will work to stymie the efforts of the GOPe to declare a nominee using a few early primary states. Its purpose is to ensure a conservative candidate is a serious contender without the rules and tricks that the RNC uses to pre-select their candidate.