Harsh realities of today means travelers may be hard pressed to go RTW on one bike without considerable extra expense and hassle. Lots of good alternatives however.

Not only is crating and shipping a bike expensive but can be stressful, a major hassle with endless document nightmares, insane invented fees and corruption.

You may also encounter massive unexplained delays waiting WEEKS to get your bike free of the port ... IMO, all this can ruin your whole trip and ramp up your expenses .... a lot!

PLUS ... you still have the Carnet to buy $$$$ in some regions (not S. America) get stamped in/out and if you screw it up you can lose a BIG chunk of deposit money ($thousands$).

The good news is you can ride your current BMW F650GS all the way South, then either sell it off, ship to S. Africa ... or ride it back to USA and sell it legally there. Or ... leave it, come back in a year or two and continue your trip.

If you do S.America as a loop you may even be able to do some "new" countries on your way back North, see parts of countries you did not see on your way South. (like Caribe side of Cent. America, East side of Mexico)

ROUTE:
On your way South stay West through Mexico and Central America, then stick to Colombia, Ecuador, Peru' and Chile. Then, if you decide to ride back, head North, do Argentina, Uruguay, Paraguay, Bolivia, Venezuela and Brazil. You could spend a year in Brazil alone.

Perhaps ship to Miami from Colombia?? ... or take another two weeks and ride to USA. Sell off that bike once back in USA. You got your money's worth!

If you ship your bike to Africa then you're good to go for ALL of Africa and EU and beyond. You will have Carnet issues to deal with in certain countries.

If you fly to S. Africa and buy a bike there, I think Carnet is not required for most other African countries with S. African plates (not sure on this, look into it). It's not cheap for bikes there but not that much more than US or EU, AFAIK.
Asia- India
Most Moto-Queros don't ride into China and it's impossible to legally bring your own bike into China. So, that's another part of the world you have to buy (or rent) another bike.

Another challenge area for bringing your own bike into is India and most of Asia. India make it nearly impossible to temp import a bike and the Asian countries also can be a major hassle. Rentals or buying your own bike is THE WAY to go for both of those regions.

Cheap and easy to buy or rent bikes there. No point bringing in your own bike. Would be a HUGE hassle and expense.

You could also leave your bike behind once you get to Chile or Argentina. I hear it' quite easy to do this in Uruguay. No hassle with TIP. They love BMW in Argentina and Chile ... so you may get an offer you can't refuse. Let the buyer worry about registering the bike.

You're so lucky to be able to take off and travel!
!Que le via muy bien!