The biggest challenge will be to have sufficient German language skills to study in Germany. Conversational German is not enough to write term papers in the language. I say this as a German immigrant to Canada who does not think that his kids will have sufficient German skills for this to be an option. But at least their are fluent in French, which may open up some government jobs in the future.
While the German university system is essentially free, entry is based on the "numerus clausus" or cut-off grade. For medicine, you basically need straight A's to even be considered. For engineering, it's a bit less but still quite high. However, a lot of people that would get into a 3rd-tier college in the U.S. would be rejected in Germany. The idea is that only people smart enough to study are admitted, so you do not have the barrage of marginally qualified liberal arts students meandering through university as walking & talking profit centres innocently mortgaging their futures.