Hmm. I can’t comment on this from a point of view of business model or numbers of learners, becasue I’m not running a business, and I haven’t seen the numbers: @aran has, and I trust his judgment. However, as a user, it feels to me to be a shame to go all the way down to a single-sentence taster.
My personal experience of using SSiW is that I came to it when there were the new Challenges (as well as the more-or-less archived Lessons) but not yet any of the newer, structured approach, having already finished everything that was available on Duolingo Welsh at the time. So I thought – mistakenly, obviously – that I already “spoke Welsh” and would just give this other course a go as a bit extra; I assumed – mistakenly – that if there was no written component and no explicit grammar it couldn’t be all that rigorous, but it might be worth giving it a try. Because I’d already done the Duolingo I don’t think there was anything in the first Challenge that I didn’t already know, although having to respond orally under time pressure (rather than some written multiple choice thing) was novel, and an enjoyable challenge. I can’t remember now, but I think I did the second Challenge the same day as the first – but by the end of the second Challenge I had begun to get the feeling of having had a real mental workout, that this really was something different.
I can’t remember at what point I changed to a paid subscription: I’m fairly sure it was before I reached the end of Level 1, and although I got grandfathered in with a good deal, I am – like @alisonspencer and, I suspect, a number of others – happy to continue to pay that sub even though I’m taking less from the site, as a way of putting something back. There’s a genuine gratitude towards and sense of community about SSiW that I have rarely, if ever, felt for any other service I’ve paid for: it feels more like a club subscription than a commercial transaction, and that’s lovely.
Having got a paid subscription I then steamed through the Courses and the Challenges at the rate of at least one a day, until within a couple of months I had reached a level in Welsh that in other languages I had taken literally years of evening classes to get to. I was unapologetically evangelical about singing its praises as a methodology to anyone and everyone – and still am. I’ve got the kids going through SSiSpanish with me now (so I do still get something out of the polyglot sub!) and, again like many others, I wish it were available for pretty much every language I’m interested in. In the competition/drive to recruit new learners I went back to being unashamedly evangelical, with a certain amount of success.
But the thing is, I’m sure I wouldn’t have made that decision on the basis of one sentence. It took me at least two Challenges – possibly more like five – to get to the point where I could feel how novel, how effective it was. I know this must be a decision taken carefully and thoughtfully, and based on the actual evidence of where new learners are coming from, so I’m sure the number of potential learners lost in consequence must be small. But I think there will be some losses – I know I would have been one. If it were up to me – it isn’t – I think I’d want there to still be a bit more than just one sentence; I could wholly understand, say, five free Challenges rather than fifteen, but I think “none” is a shame.