African-American Vernacular is trying to move away from English, which means at least one dialect has intent. Just a' the rappers
In the chorus of the 2012 song, "Birthday Song," the artist 2 Chainz raps, "They a' me what I do and who I do it for." Here, a' is an abbreviated version of aks or ask. Not all rap songs use this pronunciation, but it may be common where 2 Chainz is from in Atlanta. It's an example of linguistic drift in African-American Vernacular English (AAVE), and because that drift is so easily noticeable, it may indicate that AAVE is drifting quickly.
Do dialects have intention? Some dialects sound "snobby" and some more "down-to-earth." A study on waitresses in Texas indicated that they speak in more rural or "folksy" accents when talking to working-class customers but switch to a more formalized-sounding, mainstream accent when speaking with white-collar ones. The customers themselves presumably don't change their accents.
If individuals modulate their accents as the situation demands, do groups do so as well? If one group of people consistently has one type of relationship with another group, will their dialect reflect a desire to maintain a certain distance? Is AAVE trying to get away from mainstream English?