+1 There is no way there can be a war wiithout a terrible price. The rest of the world will do nothing, we will be massacred. Look at the support the farmers in Zimbabwe got.? Nothing. If you can leave, leave now. There is no logical alternative.
You are predicating your ‘terrible price’ on past confrontations of a similar nature. The continent was used as a proxy battlefield against communism so the enemy forces had the advantage of Russian and Cuban (and Chinese?) leadership, equipment and advice (and fighters?). The USSR is no more. The State President can technically deploy SA troops but (IMO) other elements also need to be factored into the potential for civil war. Consider:
#1 Non-blacks overwhelming hold any positions in logistics involving skill. The mechanised and technical elements of the SANDF will grind to a halt rapidly. Any war effort will depend, to a great extent, on logistics, airpower and technical know-how. Non-blacks overwhelmingly, fill these positions. And if there is no competent logistics…
#2 Consider a SANDF where the embittered ‘whites’ have been passed over for promotion etc. in spite of years of loyalty (AA for MK & APLA cadres). They are not going to be loyal and perpetuate a status quo where they stand to be discriminated against.
#3 There will be tremendous negative pressure on serving whites from friends and relatives.
#4 International mercenaries would be relatively easy to recruit. Governments may deplore the civil war but, because the situation is so bad, will not make more than a token show of stopping recruitment.
#5 There will be many SA volunteers. These are not the paunchy, brandy & coke swilling indulgers of right-wing rhetoric over the braai. However repugnant their ideology is considered, many of the younger bunch were very good soldiers (the extreme right wing may offer their combat services for free).
#6. Any support will have to be clandestine or be exposed as supporting a racist, discriminatory and autocratic regime.
#7. And so on…