Not only it’s all doable without college, but also it can be done better without college. With Coursera (and other similar services), you can take one course at a time at your own speed, which can be much faster. Without worrying about GPA, you can customize the curriculum as you see fit, going deeper some times and just skimming through other times. While inserting relevant field experience whenever it would be useful.
In other words, you won’t have to make compromises between better learning and better grade all the time. For some kids who have homeschooled for a long time, making the compromises could be an unpleasant challenge.