I think it’s more likely that we will see smaller scale attacks by domestic terrorists, ranging from mass shootings to something on the scale of a Timothy McVeigh. I can also see a probability of a return to a 1960s/1970s level of political violence and assassinations.
I think those are more likely than a large scale attack from foreign terrorists.
I think the likelihood of another major terrorist attack happening on US soil is drastically higher now than 30 years ago. But thats due to a lot of factors, primarily increased political hostility and increased population density.