I never expected Discovery to be about the Klingon War all the way through. But there are tons of examples of things introduced in the series which were hastily retconned in some way (like the bald Klingons being explained away). And while little has come out regarding behind the scenes drama from Season 2 yet, we know there were changes that were demanded by the network in Season 1. For example Si Vis Pacem, Para Bellum apparently only happened because CBS was unhappy they had gone through half the season without landing on a planet and exploring.
As for what Season 3 brings, it remains to be seen. But in some ways it's a much more dramatic retooling of the setting than even Enterprise's third season was, which we all are aware was due to a desire to boost ratings.