Scaling-up antiretroviral treatment (ART) to socially meaningful levels in low-income countries with a high AIDS burden is constrained by (1) the continuously growing caseload of people to be maintained on long-term ART; (2) evident problems of shortage and skewed distribution in the health workforce; and (3) the heavy workload inherent to presently used ART delivery models. If we want to imagine how health systems can react to such challenges, we need to understand better what needs to be done regarding the different types of functions ART requires, and how these can be distributed through the care supply system, knowing that different functions rely on different rationales (professional, bureaucratic, social) for which the human input need not necessarily be found in formal healthcare supply systems. Given the present realities of an increasingly pluralistic healthcare supply and highly eclectic demand, we advance three main generic requirements for ART interventions to be successful: trustworthiness, affordability and exclusiveness--and their constituting elements. We then apply this analytic model to the baseline situation (no fundamental changes) and different scenarios. In Scenario A there are no fundamental changes, but ART gets priority status and increased resources. In Scenario B the ART scale-up strengthens the overall health system: we detail a B1 technocratic variant scenario, with profoundly re-engineered ART service production, including significant task shifting, away from classical delivery models and aimed at maximum standardisation and control of all operations; while in the B2 community-based variant scenario the typology of ART functions is maximally exploited to distribute the tasks over a human potential pool that is as wide as possible, including patients and possible communities. The latter two scenarios would entail a high degree of de-medicalisation of ART.