Like everything else, it is a business decision.
Does it lower costs?
Does it increase revenue?
Is it easier to manage?
Is there majors risks associated with either doing nothing or moving to the cloud?
I have my doubts that you will see any return on investment compared to doing nothing.
If you were just starting the site with no established infrastructure, then it might make more sense.
It might make sense if you were doing such a major overhaul to the site that it was really a new site.
What is your current setup? Hosted on your own infrastructure, hosted in a hosting center, etc.?