Nobody can replace Silva. I've not seen a player since the turn of the century with as intelligent off the ball movement in the areas of the pitch Silva operated in (Xavi and Xabi Alonso were magnificent but played deeper).
Combine that with his close control, vision, and ability to be calm and metronomic and now he's playing like a midfield tempo setter except it's just outside the opposition area. Not only is that perfect for dominating possession in dangerous areas but Silva's movement and control means that it gives De Bruyne lots of opportunities to find himself in dangerous areas around the box.
It's going to have to be like replacing any other top, top player. You have to get in another top, top player with their own skill set and hope their unique strengths make up for the ones lost.
Funnily enough I do think we've been blessed to have possibly the only other active player to match Silva's genius movement. Although somewhat awkwardly it's Sterling as opposed to our CM options.
Also he's not as good as he once was but Eriksen is getting some harsh words. I remember when he tore us a new one for Ajax back in 2012. He was great for Tottenham too. He was the league's De Bruyne before De Bruyne. He scored all manners of goals, created lots more chances than anyone else, powered himself around relentlessly for 90 minutes. Skillful, technically brilliant, great set pieces, and scary on the counter. He's the player United falsely hoped they were getting in Fernandes.
I'm not arguing he was on Silva's level, I'd have had Dave every day of the week. But in the duration of Eriksen's PL stay he created the most assists, most chances, joint second most big chances (with Silva and Mahrez), scored more outside the box goals, more free kicks, and frequently topped distance ran charts. He was definitely good.