Everyone on my team has been using 15" MacBook Pros with 16GB RAM for the past 3 years. I suspect most developers run with 16GB of RAM just fine.
I'm not arguing "16GB is fine for all developers everywhere!", but it's absolutely not a hard requirement. I suspect for a lot of us, the difference in performance between 16GB and 32GB is trivial.
Regardless, the thing which is kind of stunning about this chip is that they are getting this kind of performance out of what is basically their MacBook Air CPU. Follow on CPUs—which will almost certainly support 32GB RAM—will likely be even faster.