Any thoughts of South Africa having people in the stadiums are purely pipe dreams. It will not happen. Vaccinating people takes time, and the majority of the big bundles of vaccines that have purchased are vaguely coming in Q2. The country's plan isn't to do vaccinations based on geography, it's being based on vulnerability and healthcare workers (like everyone else has).
The UK have actually been one of the leaders in vaccinations and their target is 15m vaccinated in about a 2 month time frame. We can only start with the first load of 1m in a weeks time. We won't be as coordinated in SA vs the UK, we have a much larger area to provide for a similarish number of people and in general government run things haven't always been the most coordinated (looking at applying for a passport, for example). (Also keep in mind that with most shots you are only at the high level of immune after the second shot 8 weeks later).
Given all that, SA really won't be in any position to have open stadiums. All things point to behind closed doors Lions tour in SA, given the inability to postpone (tour commitments, World Cup preparation interference).
My question is, given everything, are we still going to see the complete tour or something cut down (e.g. the mid-week against the provincial teams still completed). Given that the broadcasters are driving the money in this now I get the feeling yes, given the more games the more views. But let's see how it shapes up.