Primarily: Azure is already super successful and I see it taking a solid #1 over the next few years. The main reason is that Microsoft is doing what they do best: offering a product in every category. Want Kubernetes? They've got it. Need issue management? Azure DevOps. Chat? Teams. Email and Office? 365. Once you're in that ecosystem you're just going to bleed into all of their products before suddenly you're a Microsoft shop.
Moreover, Microsoft has done an extraordinary job at revitalizing the user experience of many of their products. Azure DevOps and Teams has its issues, but they're miles ahead of the products they're replacing, and truly only maybe 10% behind the 'best in class' of each category.
Compare this positioning to Amazon: AWS still only competes solidly in the cloud space, without extending out into the rest of "development team support" that Azure/Microsoft does. They were also ridiculously slow to accept that Kubernetes won the container war, and even today EKS is a comparatively garbage product when lined up against AKS/GKE (no managed worker nodes, $0.20/hour for the control plane, reliance on eksctl to do anything easily which isn't even an official AWS product, etc).
Amazon will be fine, but I worry about Google Cloud's future. They're industry leaders when it comes to new technology, no one else is even close, but that doesn't really matter when its open source and Microsoft is so quick to implement everything they make directly into Azure. Why isn't Google Cloud more successful? I think its enterprise support and respect, which isn't something you can just buy especially with Google's lackluster history in that domain.