Of the tech giants, Apple, Amazon, and Microsoft seem to be in the best shape at the moment. They make their money from selling real products and services to real end users.
Amazon is strong but not unbeatable. Walmart in particular, as well as a hypothetical alliance/merger of supermarket chains, are well positioned to break Amazon's dominance of e-commerce. But they will need the ambition and ruthlessness that has served Bezos so well. Few large American corporations still have the vigor and virility of Bezos's Amazon.
Microsoft (full disclosure: my former employer) too is strong but not unbeatable. All of their products are facing tough competition from Apple (in OS and hardware sales), Google (in online services), and multiple others (in business software). Microsoft's wins are hard fought and fair, and the competition never lags too much.