If you look back a couple of decades, you'll see that the electronics manufacturing industry went through a similar shift. Having in-house manufacturing capability was expensive and wasn't central to the business. Contract manufacturers, due to their scale, could offer higher quality and lower prices. So the on-premise manufacturing of things like computers and cell phones shifted to the largest and best contract manufacturers. A much smaller group of people (e.g Foxconn employees) still have electronics manufacturing jobs, some former on-premise employees shifted their roles into positions like design/manufacturing liason and everyone else had to adapt/find a different career path.
Cloud is a similar story. It is a major shift and it will dramatically change the IT landscape including the new number and kind of jobs that are available. Only Amazon, Microsoft and Google are investing the kind of money necessary to be major IaaS/PaaS players. SFDC, Workday and Oracle currently have a shot at significant SaaS revenue. And there will be others that carve out a niche here or there. There will also be those who embrace the new normal to become create new successful businesses (Netflix, Uber, Niantic, Spotify etc.).
In terms of there only being limited demand in Cloud roles, that will be true. One choice is to sort out which businesses you believe will make it/you would be interested in working for and then making a plan to land a job there. Another option is to look at how consumable, plentiful Cloud resources coupled with enabling increased speed/scale and smarts (i.e. analytics/machine learning) is creating new roles that one could retool for and/or is launching the next wave of successful businesses.
It is scary, but this type of shift has happened before and will happen again. The key is to recognize it and to try to be proactive in charting a path for yourself instead of having the shift limit your options.
Excellent post by @PtJD89P-qhi, thought it deserved to be seen by more people.