Eventually, these models have to change. Someone is going to start writing open data layers that replace key value points in these businesses. The companies that operate on these "gig" models do a few things that sum to a greater whole:
1) Marketed web front-end for consumers
2) Confidence aggregation / metrics for both parties
3) Payment gateway / escrow service
4) Insurance and (sometimes) materials
I think we'll see blockchain tech replace the (2) and (3)'s here. With a decentralized ledger and some form of third party "notary", you can verify ratings for an incredibly small fee. Payment gateways and automated three-party escrow services are easy with multisig transactions, and can be converted to any other currency through coinbase, circle, or whatever.
The (1) point could be replaced by an indirect revenue model, or by open aggregation apps.
(4) would then be put back in the hands of the actual service provider, where contractual liability belongs. A new business model could be born, where "Uber" simply has a nice phone app that references public blockchains to get you a driver, and sells insurance packages to drivers themselves. They wouldn't be locked down to just being an "Uber" driver, however.
I think the biggest factor is:
(5) Quality control
There have to be real consequences for gaming search/ratings/matchmaking sites. If the government is interested in policing this sort of fraud, then 1-4 above will be easier to commoditize, but in the meantime, companies need to enforce discipline and professionalism among the people filling gigs.
The other possibility is automation on the service-provider end. Once you've broken a task down enough so that a person can do it by following instructions from a cell-phone, the next step is to automate those instructions entirely. We're seeing this already with Google's self-driving cars vs. Uber, and I wouldn't be surprised if with recent advances in robotics & hardware startups, we start seeing Rosie the Robot taking over for Homejoy and Drone Delivery replacing Instacart.
The (1) point could be replaced by an indirect revenue model, or by open aggregation apps.
(4) would then be put back in the hands of the actual service provider, where contractual liability belongs. A new business model could be born, where "Uber" simply has a nice phone app that references public blockchains to get you a driver, and sells insurance packages to drivers themselves. They wouldn't be locked down to just being an "Uber" driver, however.