It could be, or it could not. I can't say for sure. However, for Americans and Canadians to move over to Europe, they also need to be willing, and I'm not so sure if they really are. If they show more willingness, then we may see some more of those paths open up, even if they'd be to smaller leagues like the Scandinavian ones (referring to Gregg Berhalter here). Certainly, one's origins aren't expected to play a part. I think there are many teams in Europe that look past one's national/regional origins nowadays. That's why I'm hoping that Marsch's appointment at Leipzig gives more of the American/Canadian coaches the motivation to give Europe a shot and maybe send out applications to European teams wherever there are openings.
Whilst Marsch's conditions were pretty much suited to him eventually ending up where he is, he still had to impress as a coach. Given that platform, he's done a great job of establishing himself. Regarding his ability to speak German, Marsch was born and raised in Wisconsin, which is as American a state as you can find (
@WI_Red can talk more about its demographics), and I'm not sure if he necessarily spoke much, if any, German, growing up. Based on his viral half-time speech, it looked like he took the time to learn German during his Salzburg spell. If anything, Marsch's ambitious nature along with his coaching and style of play made him more of an attractive prospect for coaching at Leipzig in 2018. The American soccer media saw this as a major gamble by Leipzig and a big surprise on Marsch's part (given that he technically stepped down to a lesser role). With that said, hopefully we have more of these welcome surprises and a greater push towards proactive coaching in the U.S. and Canada.
EDIT: Regarding the MLS coaching pipeline, specifically, there is one notable example of an MLS head coach moving to Europe outside of the Red Bull or CFG pipeline. Veljko Paunovic coached Chicago Fire for 4 years and has since been coaching at Reading in the Championship. Despite Paunovic only making the MLS playoffs once in his 4 years there, he was still brought into what is a fairly decent European league at a fairly decent team in Reading. The possibilities are there; it's just about the coaches' ambitions and whether there are enough of them.