After searching a lot I still do not have a clear answer on this: How to implement GAnlaytics for more than 100 subdomains.site.com? Each of my subdomains will have Google Tag Manager implemented. Also I know that the max number of views allowed by google is 25 per domain...
Regarding the Property and View limit (50 and 25, respectively), there's no way around that, really, so you'll probably have to break up the sub-d's across several properties. So with that in mind, you could have one GTM container across all sub-d's, and then use a lookup table to determine which data from which sub-d's go into which property. Within the views themselves, for each property, you would need to create a hostname prepend filter so that you know which sub-d you are looking at, as well as a hostname include filter so that you only capture data from a particular sub-d into that view.
You could also have a roll-up view that has data about all your sub-d's under a particular property.
That's the gist of it, so hope that helps.