2) at 70 he is rather old. Two of five Zambian Presidents have now died in office of natural causes and I think the major parties will go for someone younger,
I don't think this is as much an issue as you might think.
A 70 year old would still be younger than most of his southern African colleagues.
Birth Year - Head of Govt (State)1924 Mugabe (Zimbabwe)
1935 Pohamba (Namibia)
1939 Thabane (Lesotho)
1940 Mutharika (Malawi)
1942 Zuma (South Africa)
1942 Dlamini (Swaziland)
1942 dos Santos (Angola)
1943 Guebeza (Mozambique)
1944 Michel (Seychelles)
1944 Scott (Zambia)
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1947 Ramgoolam (Mauritius)
1950 Kikwete (Tanzania)
1953 Khama (Botswana)
1958 Rajaonarimampianina (Madagascar)
1971 Kabila (DR Congo)