It’s a stretch today but these things change quickly. Mobile telephony became a substitute to ILEC telephony rather quickly. Mobile broadband requires a lot more spectrum, but I suspect it will be “good enough” for most Americans, just like mobile telephony was “good enough” even though it wasn’t as reliable as ILEC telephony.

Therefore, tacit collusion won’t be feasible because mobile broadband is increasingly in competition with with landline broadband providers (like Comcast and Charter), and possibly even media companies (like Netflix and Disney).

I’m skeptical of that argument. There’s obviously some overlap in terms of delivering content, but in general they provide pretty distinct services given the devices involved and it’s unlikely that the landline broadband providers are going to provide much competition for three dominant providers in a mobile market.