I'm thinking the other way, the fight will not be in slow down phase from the early rounds until the end to settle the score between them without any issues, they should try winning each round as much as possible. There's no need for them to wait on the usual testing skills before releasing their main strategy which is to try to always make a successful blow.
They already met twice, know each capability, know each other, know everything, and many more. Once they stepped onto the ring, they will exchange blows right away and who's the last man standing will be the winner.
This is a third fight between the two. So you are right. Both of them will be having a fair idea about each others strengths and weaknesses. And the match will go down to the wire. IMO, these are two evenly-matched boxers and in all probability there will not be any clear winner. A KO seems very unlikely and the most possible outcome is UD. I won't be surprised if we get SD as well.
BTW, DAZN just published this article:
https://www.dazn.com/en-IN/news/boxing/who-won-canelo-vs-golovkin-1-our-three-judges-rescored-the-fight/14jgx099i1hyp1xftcxjcqhuolThey asked three renowned judges to re-score the first fight between Golovkin and Canelo. The scorecard is as follows (by judge):
Chris Walker: 117-111 for Golovkin
Matt Astbury: 116-112 for Golovkin
Steven Muehlhausen: 116-112 for Golovkin
And this was the official scorecard from the match:
Dave Moretti: 115-113 for Golovkin
Adalaide Byrd: 118-110 for Alvarez
Don Trella: 114-114
It is very clear to me. Golovkin was robbed of a win, not once but twice.