Every NOT-FOR-PROFIT organization should have a mission, and if it accomplish its mission, it is supposed to be winded up. But commercial companies would try to to find another profitable mission for the interests of their stakeholders. I cannot imagine that LingQ will start to sell mobile phones or something. The existence of paying members does not necessarily mean that LingQ is a commercial site.
I hope that many more members will become PREMIUM members at LingQ.
LingQ is indeed a commercial site. LingQ does not have public funding nor a sponsor or independent source of money. LingQ may appear to be a philanthropic organization committed to helping people learn languages, but this is not the case.
LingQ is committed to creating a product, namely a learning community, that people will want to join and contribute to, so that LingQ will prosper and get better and better. LingQ hopes to cover its costs from member contributions, so that it can continue to invest in making the community better and better. At the speed that technology is progressing, I do not see the day when our development at LingQ will stop and that we will look for another field of endeavour like mobile phones. We are committed to language learning, and to the language learning revolution. Let everyone in the world learn many languages, not just English, and understand each other better.
There’s no need to branch out into mobile phones as long as you can keep adding languages. Looking forward to your adding Akkadian and Sumerian, Steve. 
We will need to find a few speakers to record their voices and create a library first.
"I explained that we are, after a fashion, a for-profit corporation, since we do not have government funding. "
Not having government funding does not mean that an organization or an association is a for-profit corporation. On the other hand, some companies have government funding, and they are still called for-profit corporations. I know you prefer to use the expression “for-profit corporation,” and I don’t mind.
"LingQ may appear to be a philanthropic organization committed to helping people learn languages, but this is not the case. "
LingQ does NOT appear to be a philanthropic organization, but I see that many of the members are helping each other, not for profit.
Should LingQ ever consider becoming more commercial, some sort of advertising arrangement with an online bookstore which sells audiobooks and ebooks would make sense. So that when we recommend books on the forum there can be a “click to buy” button.
Whether we would generate enough traffic for it to be worth it, given the great diversity of LingQ members’ interests, is another matter. Depends how eclectic the bookstore’s catalogue was I suppose.
“LingQ hopes to cover its costs from member contributions, …”
Nobody thinks that this is wrong. Is this the only reason why you consider LingQ to be a commercial site, that is, a for-profit language-learning community?
Helen, we would need much larger numbers. One day perhaps. We could even get samples from them maybe!
Yutaka, I do not consider being for profit wrong.
“I do not consider being for profit wrong.”
I don’t disagree with Steve on that.
In the first post of this thread “if it accomplish its mission” should read “if it accomplishes its mission.”
If the word “commercial” is related to the “buying and selling goods and services,” I am buying writing correction services by LingQ. On the forums at LingQ, we exchange messages for free, and LingQ provides us with the BBS system for free. I think that without some lively interactions among the members you cannot call a learning system or the content at LingQ a community. The community aspect of LingQ lies in the lively forums, and they do not appear to be commercial.
Reading this thread reminds me of a story:
One day, a priest asked to his superior if he could smoke when he prays. Obviously, he’s superior said no. Disappointed, the priest talked to his friend which told: “You asked the wrong question! You should have ask if you could pray when you smoke.”
It’s the same for Steve with his way he presents LingQ (commercial, for profit, bad capitalist corporation) that government funded (communist) organization don’t want to help. I don’t know, try to present LingQ as a non-governmental-organization that covers its costs of activity with paying members (and don’t say you’re for profit). Maybe it will make government funded organization less “boycottive” of LingQ if it’s presented that way.
Just my two cents