Space Marine 2 was a solid game but it ultimately played it safe, so 3 NEEDS to take risks and push the series further.
Just... don't be the pipeline of Dawn of War 1>2>3.considering how long it took them to make a 2 i don't mind them playing it safe so much (you might as well treat it as the first entry outside of the story) but yeah DO COOL THINGS INNOVATE TAKE RISKS.
You have near infinite money and a dream IP to work with give us actual insane shit maybe the next game we shift perspectives as part of a rare cooperative action between two space marine chapters
Having someone look at Titus with an outsiders perspective would be intriguing and would give a good excuse to introduce more and new war gear for the player Titus's fat ass in an assault pack (working exactly as bad as ive heard) while the white scars laugh at him and charge ahead on their bikes (which the player get's after said mission)
on't care about the lore let the player have a arsenal of every cool toy in the WH setting.