Have you read this book? If so what's your take on the book? especially the believe that in 4 to 5 years Africans from Rwanda, Eritrea, Kenya, Ethiopia will start to dominate Tour De France riding?
Many people don't know that Chris Froome was born and raised in Kenya till he was 14

Not likely.

Why you think so Bob?

Seriously? More is made of that fact than of his winning the TDF.

In the modern sport it takes more than raw talent to even become a member of a Pro Tour team. There needs to be significant infrastructure in place and riders need to be able to work within the cycling culture, at the elite level, just to dip their toe in the top echelon of the sport.

With the exception so South Africa that just doesn't exist on the African continent. Even if you look at the considerable number of riders who have done well coming from North American, Australia, New Zealand and, as I mentioned, South Africa, the vast majority of those riders came up through European teams. They cut their teeth on European squads even if they spent some of their time racing outside of Europe.

You need only to look at Asia to see what I mean. There are several Asian riders who are attached to European squads at the Continental or even the Continental Pro levels. They may do some racing in Europe and some racing on the Asia Tour circuit, but, as far as I know, there is only one Japanese rider on the Pro Tour. Although I have seen the level of racing here improve dramatically over the last 15 years, and although there are a few billion Asians on the planet, Asians are woefully underrepresented in the top level of the sport.

Accepting that and also accepting that Africa is decades behind Asian in this regard I don't see how it would be even remotely possible for African riders to make any impact on pro cycling regardless of raw ability.

Very valid points:
But one thing I have to add is that Africans have natural talent compared to Asians and what they lack is infrastructure, support and coaching. UCI now sponsors/supports African teams and Chris Carmichael is also training these African teams including others.
The book mentions that Frank Shorter was the best American marathon runner and dominated the sport until one Ethiopian won and that opened the flood gates of Kenyan long distance runners.

Dude! It's a big achievement to Kenyans. You probably wouldn't understand.

I am talking about culture, not race. I think it is very important that we make that distinction.

East Asian cultures, generally, don't place much emphasis on sport. Sure, there are some areas and some sports where this is not the case, but on the whole these are not to a level that creates environments where sport is a legitimate pursuit for children.

We also have to set aside government run sporting programs aimed at Olympic sports. Very few of those sports have professional levels that an athlete can aspire to.

The UCI has been working in Asia for more than a decade. Heck, even tiny Taiwan where I live and have raced for the last 15 years now has three Continental teams. There are teams in Hong Kong, Malaysia, the Philippines and several Continental Pro teams in Japan. There are also National teams from almost every country on the continent (I've raced against the Iranian National team, for instance).

There is an entire UCI Asia Tour calendar developed specifically to promote the sport in this part of the world and to give Asian riders access to a much higher level of competition and the opportunity to develop within the cycling culture. I can't stress this enough as there is A LOT more to being a pro than riding your bike. A lot more.

All of this infrastructure has produced pro riders from Asia who are now, a decade or more later, racing in Europe at the Continental Pro level but that final step has only been made by a handful of Asian riders.

Now look at Africa. With the exception of SA, there is only one continental team on the entire continent. There are few races and few national teams. The sport is in its infancy there. Even if it develops there faster than in Asia, which would be remarkable given the economic challenges alone, it will be quite some time before African riders are present in any numbers in the Pro Tour never mind having a significant impact.

It's not about race but we can't ignore natural talent and I think these Africans have that but as you said, it's takes more than talent to be good in cycling. The sport is very new to these Africans and they depend on sponsors so yes there are some steep challenges. Also these governments are corrupt and frustrate athletes just like Froome had to move to SA to develop his talents. There is Daryl Impey who made history and I won't be surprised if SA becomes the path to TDF for these Africans.