I honestly don't understand why the other nations won't create their own templar forces.
Seriously, Tevinter STILL exists and furthermore, the quanari are integrating their mages into their attack forces now. Hell, as per inquisition, the quanari are actually incorporating templars AND mages into their fighting forces.
How exactly does Neverra or Kirkwall actually deal with either of those two forces WITHOUT their own templars? They don't have their own mages and the chantry has no templars so I do wonder how the Chantry actually does anything. Remember, in previous exalted marches against Tevinter and the Quanari, the templars would've been at the forefront of the fighting and given that the chantry was considered independent, as a rapid reaction force of highly trained knights,they could respond much, much faster than any other nation.
If say Antiva is attacked, in a post Inquisition world, the Divine has to wait upon the other nations to marshal forces, worse, there's a very good chance many of them will ignore/procastinate at said call for action (I doubt Fereldens for example are going to send their sons/daughters to fight in Antiva quickly)...the Chantry can't quickly respond since it has no army anymore.
re: Corruption
Why would the college of enchanters be LESS susceptible to corruption than the previous system? In the previous system, there were two sets of oversight possible - the seekers and the chantry. The college has no-one yet it is going to be LESS corrupt? That makes no sense and has never been true in human history....