I think we can safely assume Dear Evan Hansen will win the Grammy at this point. The only other scenario I see this not happening is Comet being nominated and Josh Groban really wanting to be able to finally put an award on his mantel causing him to actively campaign for it.
In the past several years unless the musical is a cultural zeitgeist, an album with star power/connections to the commercial music industry will usually will win over a show an artistic (Better) score.
Examples include:
2017: The Color Purple- The fact that this was the only album with are 3 "principle soloists" including Cynthia Erivo, Danielle Brooks, and Jennifer Hudson, while only Carmen Cusack was the only principal soloist for Bright Star, Danny Burstein for Fiddler on the Roof, and Jessie Mueller for Waitress. Although this production of The Color Purple sold tickets on the trio, the show itself is almost carried mostly on Celie (Errivos) back. Add to that that Kinky Boots's West End Cast recording was nominated.
2015: Beautiful winning over Hedwig with The Bridges of Madison County, and If/ Then not even being nominated.
2014: Kinky Boots winning- with only Motown and Matilda being nominated excluding even nominations for Cinderella, Pippin, Hands on a Hardbody