How to Deal with Populism

Brexit and immigration is a good example of this. Blair decided mass immigration was a good idea for a number of reasons. At some point they surely realised that although it would provide an economic boost, some people would lose out financially and most did not want significant cultural change in their community. Over the years larger dissatisfaction with this policy grew and grew, only to be labelled racist by the ruling parties. This led to UKIP which led to splits in the Conservative party which led to Brexit.

Ignore a valid issue long enough and resentment will spread across the country. If these peoples concerns and wishes were not sacrificed for ulterior motives a EU ref would likely never occur.

Parallels to US/Trump seem reasonable. Large groups of people whose concerns have not necessarily been address because the contrary policies benefit an already privileged and distant few.

tldr: Offer real solutions to the large number of poor and struggling people in your country. Even if it slows down your grander plan. If you don't, resentment will build and there are more of them than you.

edit: The absolute biggest danger to the embedded powers is that Trump succeeds and does a good job. Hard to overstate this.