If you had one question to pose to the executives running the biggest cloud implementations in the world, what would it be? It’ snot really an idle question. Next month in San Francisco, the cloud chiefs from Amazon(s amzn), Google(s goog), HP(s hpq), IBM(s ibm), Rackspace(s rax), Red Hat(s rhat) and VMware(s vmw) will be on stage at Structure June 18-19. So after a highy unscientific query — on Twitter, on Facebook, via email and phone with industry sources  — here’s the list:

 1: When will all the major clouds support the same set of APIs?

2: When will they support migration of data/workloads from one cloud to another natively?

3: What comes after the race to the bottom in cloud storage prices plays out?

4: When will we see a true cloud exchange? 

5: How can we be sure our data is safe in your cloud from prying eyes?

If there’s a thread in here —…