Yes, they know that theyve upset the whole original fanbase for diablo (generally people in my age, 30, and who loved d1/d2) greatly with shitty d3, fiasco immortal announcement, so for sure they wanted to regain some good will by really putting emphasis on this D2 resurrected remaster to win us back. If we're gonna be real cynical I guess they know that we are a financially strong consumer base after all as we have jobs... I feel it was parts due guilt, parts due PR/Good will, and parts (most importantly?) to build faith in Diablo 4.
But D4 is ofcourse their future for the franchise, it's what will make them (and their stockholders) money... Thinking d2r will outsell d4 is just... no. You need a reality check. Go watch twitch and look at popular games.