Or, in other terms, removed stable jobs from the economy and replaced them with risky ones that require workers to provide their own capital with no promise of reward.

Entrepreneurship in the sense of forcing low-wage workers to provide their own capital and take on a disproportionate share of the risk, while the company itself makes money with relatively little risk, is not a good thing.

If Uber didn't do it, someone else would.

Go into business for themselves? These centralized platforms even set the price on behalf of their "entrepreneurs". They can squeeze providers anytime, as Amazon squeezed publishers, as Apple Facebook and Twitter pushed around app developers etc.

Don't be fooled. This is the dynamic. Centralized platforms squeeze producers and make them compete globally. Jobs shmobs. As soon as self driving cars go mainstream, all those jobs will be gone.

Providers will alwas be squeezed. We as a society should stop expecting everyone to produce in order to not be homeless. There is no economic law that says demand for human labor will always be high. We need to tax the machines to fund unconditional basic income.

This is the key. I can't imagine that "gig economy" services like Uber see this new job market they've created as anything but a temporary inconvenience to be done away with as soon as autonomous systems can do the job instead.

Like you say, if we haven't started to at least get comfortable with the idea of a basic income by the time autonomous systems start replacing human jobs wholesale, things are going to get scary.

I'm not even sure that's really the case; taxi drivers were already largely theoretically independent operators contracting with the cab company which provides dispatch, provides the vehicle under a lease arrangement, etc.

It is truly a new class of "job" -- with pluses and minuses (the distribution of positives and negatives are up for debate).