This is already the case in Europe though; if anything, the racism/discrimination situation seems better than the US, since you don't have to fear for your life if you're black and see a cop.
I'm not sure there is a "nice" solution when some people immigrate for the sole reason of freeloading on the welfare system. I've noticed that in France where some people do not even wish to integrate (the tools are there if you want it), and prefer to stay within their community, relying either on welfare, or will often transition to living off crime (drugs, etc).
I am not sure black people in France are not afraid of police. If you exclude ugly episodes like this one:
https://www.independent.co.uk/news/world/europe/french-polic...
Being black nevertheless means that police stops you very often, speaks at you with some rudness ("tutoiement") and police in general is white and close to far-right mindsets:
https://translate.google.fr/translate?sl=fr&tl=en&js=y&prev=...
USA partly managed this internally but it started from migrants not received them. Even then there are major ghettos and cultural differences there.
It is not at all about local populations being welcoming or not but about migrants not wanting or being able to assimilate. Clustering together exacerbates the problem.
Contrast to eg. Denmark where immigrants can enter the country and do absolutely nothing, and get a full upkeep with free housing, schools and health care.
And here the problem is that some of these people like it that way and don't even try to get a work and teach their children how to get work (eg. by learning the local language and other social norms, like that women are considered equal).
Leaders in Europe have recognized the need for this attitude in the past, but they've acknowledged that it hasn't quite worked out [4][5]. Making the transition from a country with very long family lineages just requires a lot more convincing of the local population.
1: https://www.theatlantic.com/magazine/archive/2013/11/assimil... 2: https://www.theglobeandmail.com/news/politics/canada-near-to... 3: https://www.nytimes.com/2015/12/09/business/international/fo... 4: https://www.bbc.com/news/uk-politics-12371994 5: https://www.theguardian.com/world/2010/oct/17/angela-merkel-...