Simple. No sitting on spectrum or it is forfeited. And there should be limits as to how much a single company can own to ensure there is competition. The bidding should be the first and last place where we see competition.
What would competition do? If you have 6 companies but because of that none has adequate bandwidth you are going to have the choice of choosing six shitty services. That's better? People seem to think that bandwidth is this magical unlimited thing.
No, what would happen is instead of 2 companies hoarding the spectrum and while having ample bandwidth STILL cap the snot out of service and gouge with massive overage fees, you take that same number of users and spread them across multiple companies for better distribution of users across the spectrum. And because you have more companies competing, they can't treat their customers like ass quite as easily.
Having 1 or 2 companies with the vast majority of spectrum doesn't result in higher speeds or better service, it results in the current oligopoly of higher prices, degraded service and the worse customer service in the history of customer service.
Who is saying they are hording spectrum? Holding on to something until you are ready to use it is not hoarding.
Are you playing stupid or do you honestly think Verizon and AT&T are buying up massive swaths up spectrum to "hold onto it until they are ready"? You don't think this has anything to do with warehousing to keep competition out of the industry?
They should deploy or forfeit the spectrum and pay a "spectrum squatting" penalty 2X the value of the spectrum. Those penalties go into a pool for loan guarantees for startups. Simple. No buying up spectrum and sitting on it for years. If you do, taxpayers through regulation make sure it isn't profitable.
Don't buy it unless you have plans to use it PROMPTLY. 2-3 years is enough to show deployment progress. "Intent" isn't going to cut it because the telcos like VZ and AT&T are a bunch of frakkin' liars and cheats who have made a business stealing from taxpayers.