Actually the chart isn't too far off, there is a third group of anointed, that co-incide with your third group in position except they're not - yet - part of "this generation". Ds:
Living contemporaneously with the partakers are of course a whole slew of humans. some past 117 years and counting. Only past 2055 will wt have to look for new recruits to overlap the 2 nd group that are slated to live to 2075, as of current wt teachings.