Even as Amazon.com Inc. and Walmart Inc.’s Flipkart, weigh draft e-commerce rules that seek to restrict online marketplaces — not just theirs, but also the planned super-app by India’s Tata Group — a new existential threat lurks around the corner: a state-sponsored open network for digital commerce. Commerce Minister Piyush Goyal has set up a committee to “democratize digital commerce” and “provide alternatives to proprietary e-commerce sites,” according to a ministry press release.