Short answer: No, Im not concerned.
The same question was asked when payroll providers started using admin (if you can even call it that) as a loss leader to capture the payroll service
The same question was asked before and after the DOL slammed the door on the fingers of the Open MEP providers
The same question was asked when some bigger national players started gobbling up every mid size service provider they get their hands on
These services will be a good fit to some plans, but nowhere near a majority.
My clients are with me because of the service I provide, not because I'm $10 cheaper than the other cookie cutter providers. If a client is only looking at cost, they wouldn't sign with me in the first place. We are not the most expensive, but we aren't on the low end either. One of the biggest complaints I hear from people coming from the big national TPAs or payroll providers is that the service aspect just was not there. It was hard to get a call back, their rep kept changing, they were not flexible enough, "we dont do that" was a common answer, and so on. That is not how we work. Most of my clients have my cell phone number, but very few "abuse it". My clients know that if there is an issue that needs solving it will get solved. They want and expect a premium service, and for that they need a premium service provider.
If you are a small shop that does mostly very simple admin, that may be different.