You must be joking. The largest Nilotic groups in Kenya are Kalenjin and Luo and they're farmers not pastrolists.Bantus are 70% of Kenya, nilotes are 25%. Cushites (somalis,oromos) will double in size, same as nilotes.
Kenyan bantus will be fucked over by expanding pastorals, whether cushitic or nilotic.
Don't forget that 90% of Kenya's population resides in the fertile lands inhabited mostly by Bantus and Kalenjin. Even in a 100 years this will not change.
The Somali majority NEP is barren arid lands that cannot support massive population.