No, it doesn't work, not outside the simple Flask development server.
WSGI servers scale in two ways; by using threads or by forking the process. A global dictionary is not a thread-safe storage, and when using multi-processing changes to globals are not going to be shared. If you run this on a PAAS provider like Google App Server, the processes aren't even forked; they are run on entirely separate machines even.
Use some kind of backend storage instead; a memcached server, a database server, something to control concurrent access and share the data across processes.