Analysis of information sources in references of the Wikipedia article "Trident (software)" in English language version.
Microsoft is committed to supporting Internet Explorer mode in Microsoft Edge through at least 2029, on supported operating systems.
SharePoint Designer doesn't use Trident. SharePoint Designer, Expression Web, and the next version of Visual Studio's Visual Web Designer (code name Orcas) all use the same standards-based web design component. This component was developed jointly by the three product teams for high fidelity rendering of web standards like CSS, XHTML, as well as ASP.net.
The new Microsoft Edge is based on Chromium and was released on January 15, 2020