So here's the main problems with the theory that manufacturers are going to rush back to the US and build here: Money, time and politics. First, it takes significant investment to build a large, efficient plant that manufactures whatever. Second, decisions to do so are not made by most big companies on a moments notice... their capital outlay time frames are usually measured in years, not weeks or even months. Lastly, the biggest factor, politics. During Trump's first term, some of our large multinational firms (e.g. Nike) went with the flow and moved most of their production from China to Vietnam. Now look where that got them. They're still getting pounded with tariffs. Moreover, based on the ever-changing noise from the Oval Office, Trump may just be wanting to force other countries to the negotiating table. If that happens, then the tariffs could disappear or the problems ameliorated. Meanwhile, if Nike decides to move manufacturing back here (highly unlikely anyway given the huge disparity in wages), then they're once again stuck holding the bag.
From what I read, most MNCs are currently taking a wait and see attitude. Which means no massive influx of manufacturing here at least for now.