Believe it or not, this is actually doable for Trump in 2020. He has four years to flush the voter roles of illegals. Limit voting to legal, breathing American citizens and we have no idea how many states he will win.
A 49 state landslide is not possible for anyone, Democrat or Republican. There are some states that will never go blue (WY, ID, KS, ND, SD, etc) and some states will never go red (VT, RI, MA, IL, NY, NJ, CA, OR, WA, etc.).
This is not 1984 when even many Democrats at least had some love of God and country in them.
Even if Trump somehow overcomes all these protests, the disapproval of a majority of people and the obstructionist congress and makes America great again, Democrats, and blacks and hispanics will still hate him and those blue states will still go overwhelmingly against him.