Not as all immediate changes, no, but as potential long-term reforms they would be doable.
Part of the professionalization of the Templars would be to distance them from the Chantry somewhat. Less religious education (mages and sin), more practical (mages and danger of abominations). Secularization would be institutional rather than personal for some time, but the biggest issue will be the ties to the Chantry. The Chantry is the only international institution with the legitimacy for a Circle system, and the Circles and Templars both need that- and the Templars do have a secondary role as the Chantry's guardians, which is how they interact with the world. Remove that and the Chantry will fund/supply another force, which would likely mean less support and less legitimacy for the Templars. This causes more problems, especially if the Templars become dependent on mages for financing. For the foreseeable future, Templars and Chantry will likely be tied together, though 'Templar, Watcher of Mages' and 'Templar, Warriors of the Chantry', may distinguish themselves.
Abolition of the Tranquility ritual strikes me as redundant since it can already only be legally done against consent by with sanction by mage authorities as well. With the creation of the cure, it makes even less sense, and will likely be replaced by execution regardless. Mages who can't pass their
Of course, a long term goal I'd encourage would be the actual non-tranquil stripping of magic (or, yes, giving everyone magic), which would render tranquility moot as well.
The Annullment is another thing that is a bit redundant: it's a reflection of the incompatibility or effective revolt of a Circle which other measures have failed. I am certainly for more restrictions on its usage, and more use of alternatives, but saying you'll ban its usage is effectively saying you'll tolerate rebellion and an inability to enforce order. A Circle won't be allowed to free itself from the system, and in contexts like DAO where there actually is rampant abomination the alternative to going out and clearing a towerful of demons is... well, not doing so, and the demons breaking free. That's nice for the demons, but not much else. Annullment is, in effect, an invasion of a Circle you've already been ejected from, and banning that is saying you'll accept it.
I would rule that Annullments should spare those who surrender unconditionally (like the ones Cullen accepts in DA2), but there would be other restrictions and losses of rights on such people. The prospect of agitators, blood mages, or hidden abominations would just be handled akin to a police state, rather than by an execution squad: being a survivor of an Annuled circle is not a ticket back to normal Circle society. At least not until hidden abominations can be reliably found, and blood magic identified.
I would allow Mages access into the Chantry institution (it doesn't really have anything to govern)... but only as part of a compromise deal in which non-Chantry mundanes enter the Circle's governance as well (actual governance, not Templar oversight), the mages have restrictions in how much placement they can claim, and the Templars watch them both for signs of blood magic influence. Don't get me wrong, I would give mages inclusion- but the dangers of claiming control of the oversight would also mean restrictions of that inclusion. Mages would never be allowed to rise in ranks of the Templars, the Seekers, or any who commanded them (which includes the top).
However, the keys to all of these things you would like could be enabled by future discoveries and developments, which I would promote. Being able to identify demonic possession that's remaining hidden, or identify blood magic use with ease, would be game-changing factors in the security precautions against them..