perhaps people need to like walk down memory lane to understand what these 'languages' or 'cultures' are... they are accidents!! I have travelled widely across africa and I have a keen ear. I listen and map people. I have my own theory (which is so far standing and seems to explain why we are as we are - but that is a different question). Our ansestors migrated not kwa uzuri but wars, disease hunger, over population e.t.c. and by accident isolation created some of the languages we have. For example - my trip to South Sudan helped me understand the nilotic people (eastern and western nilotes) and their origin and language structure. it even assisted me understand the bantus as there are a number of equitoria people over there. as people migrated - small changes brought about by accents (best example is the Embu, Kirinyaga and Kikuyus) were magnified as time passed and as they interracted with other groups they took stronger elements from those other cultures and kept the ones that made sense. I am sure there was some guy who first shrubbed something and the kids took on the dad's shrub as being truth. That may explain why Kyuks say "mbura" maragolis say "imbura" and as far south as south africa it's known as "pula". Zimbabwe means "house of stone" like "zimba"... "nyumba" "bwe" as in "jiwe". Pigs "nguruwe" are known as "kolobe" very far south.
We have the Kikuyus who like thumping their chest over circumistion as if Abraham's other name was Njoroge got it from the Maasais who in turn got it from cushitic people. People who never had access to the cushitic people (or migrating people who had contact with cushites) never traditionally practiced circumsition. I am in UG now and circumcision here is not a big deal. The Twa of congo picked up languages from the bantus and moved on. No one before these "wahengas" you keep on talking about moved on with life by looking back! if someone came with iron working they embraced it. if you go down south you find bantu people there who passed through the San and Khoisan people - you find elements of their language. LIFE WORKS BY MOVING FORWARD NOT BACKWARD. We now are at an unprecedented period of time where people are doing interactions daily that wahengas took many years to achieve. All those Wahengas thought their people were living where they are ad infinitum. the Kikuyu/dholuo people are speaking is an accidental product of migration and isolation or sometimes interaction with others. I am sure the Wahengas were looking at the youngmen speaking the sheng of their time a mix of Arabic and some bantu language and saying... MAKE UP YOUR MIND!! DON'T MIX THESE TWO LANGUAGES... MKOSA MILA NI MTUMWA (using some ancient bantu language) in much the same way old people look at the young with sheng. The product of which is Kiswahili and we have some enforcers telling us not to mix kiswahili with some other language in order to keep it's integrity--- what integrity? My point - there is nothing new happening... it's just happening on steroids. Our languages will die and join latin soon simply because LANGUAGES ARE UTILITIES and they either morph into something useful or die and are forgotten. unlike those people who underwent these evolution in languages - WE KNOW THESE THINGS, we are now able to self determine instead of being irresponsible and letting "things flow".

Ditto

It is also important to differentiate "modern" and "culture" some people mix up concepts. The Japanese are steeped in their culture and language and are a modern and thriving nation, more economically stable with higher per capita income than all English speaking nations, In Singapore Lee Kwan Yu used Confucian culture as a foundation particularly for ethics and family, The Chinese, the same, go to norway ni hivo hivo, whatever makes one think English in a necessity and "dumping their culture or language" is "advancing", is one of the biggest lies one can tell themselves. Modernization is not directly proportional to western culture, hio ni hesabu ya utothi kidogo, these are totally different things, it's like those blonds who argue "go and put on an animal skin" when you talk about culture, they can't differentiate between, dress, language, the economy, e.t.c, they are advancing inside an English speaking "advancement bubble" whereas the reverse is true and people are earning from their cultures.

by the way... what is the point of a "language"? it's to communicate - right? for better or for worse we have english spoken more widely... is knowledge of english an asset? Do you see a future where a person in Kenya will not know how to speak english? if a language's primary reason of being is communication - why not embrace a widely spoken one? our children will learn these things... they will look around and pick a predominant language upende usipende! kinda like I did myself... Kikuyu is the language my mum and dad spoke to me in the evening.... as soon as I stepped out of that door I met all manner of people... in our plot and in school and church.... for 8-10 hours i was immersed in swahili/sheng and in the evening again.... kikuyu for like 4hours or less. My brother and I spoke swahili to each other and answered back in swahili! the only time i felt lack of knowing kikuyu was a problem was when I travelled to shags... my kids will not travel to that "shags" they will travel to Nakuru town as their shags or Mombasa as their shags - they will not feel the need to speak that language. most of us have travelled long distances from where we were born originally and look around... this will be shags for your grandchildren.... apartments and gated communities. someone will call donholm shags! this is of course assuming that they will care to travel to shags!