Hello there
I don't believe that the human race will be alive for the next ice age. The next ice age is more than 15 000 years away according to evidence from an Antarctic ice core the deepest and oldest ever extracted. The core gives us a 740,000-year record of the planet's climate, including the past eight ice ages, and interglacials, the periods in between.
Basically in the next 15000 years I believe something along these lines will happen:
There is life on earth because of an accident. This accident is caused by what we call the 3 conditions:-
1. Things have to make copies of themselves (through birth or other ways), this is called Replication
2. They have to make small mistakes when they replicate, this is called Mutation
3. These mistakes have to be the same in their copies, this is called Heritability
Basically, these conditions are very rare, but they are possible and they cause life. I believe that these conditions, as rare as they are, will afflict mankind in the next 15000 years. It sounds rather science-fiction, but it can, and has, happened. If this does afflict humans, whats not to say that the mutated man will mate. The mutation area could afflict sexual organs, meaning a single creature could mate with itself. This would mean that only one mutated human would be needed.
This is why I personally dont believe that the human race will be alive for the next ice age. However I DO believe that another, more adapt form of makind will be alive for it. Or maybe an even less adapted creature.