Re: Can AIDS be cured as long as . . .
Thus far, there is no cure for HIV. However, if by "cure for AIDS" you are referring to individuals with clinical manifestations of AIDS (CD4 T-cell count under 200; a variety of AIDS-defining opportunistic infections) "bouncing back" to a functioning immune system that can keep opportunistic pathogens in check, this is obviously possible with appropriate medical interventions.
How would anal sex between two HIV+ individuals impact upon this recovery? So long as they correctly used intact latex condoms, there would be no impact at all. If they were having unprotected anal sex, there is a small chance of superinfection (being infected with the partner's virus). Thus far, superinfection appears to be relatively rare, but still possible. If one partner is superinfected with a more virulent virus, or one with mutations that confer resistance to drugs to which his primary virus was susceptible, there could be negative consequences. Whether negative consequences materialize, and their impact on future virological and immunological responses would vary from case to case and be completely dependent on the situation. It is important to note that the exact same thing can occur as a result of vaginal sex between two HIV+ individuals (and perhaps oral sex, though the risk appears much lower).
There are too many variables here to give an answer that would occur in all situations, but in general: (1) there is no risk that protected anal sex will impair an HIV+ individual's immunological recovery; (2) there are no "special" HIV-relevant dangers that occur from anal sex that do not also occur from vaginal sex; (3) there is no reason for HIV+ individuals to abstain from protected anal sex