Not sure if my input's still welcome here, but...
First, I think we should all give a huge amount of credit to Joaquin for keeping this money-pit of a game going for the past five years. Unless something's changed (Doesn't appear like it), I don't think this game has ever turned a profit. He started off with (I assume) just one server, and has steadily had to pour mucho dinero into adding more servers, more features and random stuff to make the experience just a little better.
There's a huge issue with people not wanting to pay for mobile apps and games in a way that doesn't happen with games that they take just as seriously on a console. Anyone on this forum's put more time into this game than they would into most games that they'd pay $60 plus add-ons for. There's no good reason for money to be an issue, but it is.
On that note, maybe it's time to re-visit DF Elite. Putting out a console quality game would be the best way to (eventually) turn a profit. From what I've seen reading a few posts, this game is reaching an older audience, and presumably a wealthier one. Assuming that the estimated cost to produce DF Elite hasn't gone up significantly from $150k, and Paul's offer still stands, maybe it could be done. Reaching out to veteran groups and other flight forums would surely bring in some real cash. We got 2/3 of the way a couple years ago, is it time to try it again?
In regard to the present issue of the servers, I hate the idea of payed and free servers. It creates a number of issues that would be ultimately detrimental to the cash flow of Echoboom. It may discourage new players from continuing once they get fed up with the laggy servers. It prevents the experienced players from acting as moderators and role models for the noobs, which could create a COD style atmosphere among the "lower class", which would be awful for everyone.
That being said, this may be a necessary evil. Without the servers that Microsoft has been providing for the past couple years, Jouaquin has to fuel the server fire with twenties at an ever increasing pace. Charging a few bucks per month would be awful, but far, far better than nothing.
The only alternative I see (unless someone wants to shmooz Microsoft into giving the funding back - looking at you, Paul. Always the charmer

) is to try to fund quality severs for everyone though the small group of people on the forum with the dedication and cash to do that. This, of course, creates issues with ever being able to put out Elite, even if Joaquin could bring in enough cash from here.
Lesser of two evils, I guess. Which one is lesser, who knows. Either way, I think that Elite should be the final goal, as that could turn a real profit for once.