Update: I was unfortunately not aware of Shamus Young's severe criticism of Fallout 3 available here to link in the original piece and I regret that. It dovetails rather nicely with what I've written and it's much better executed than my piece. I strongly recommend anyone...
Higher system sales naturally lead to more software appearing on a given system. Naturally, owners of an underperforming platform get excited to see a sales boost here and there. The PlayStation Vita the excellent March that we all knew was coming, and the effects of its newly released software and price drop carried into April as well.
It did begin to taper off a bit, however, as April had three weeks with no new game releases. For the week ending April 21st, the machine only posted about 15,000 units sold -- well below what Sony is surely hoping will be the new baseline for the system. After all, 15,000 a week is even less than what the 3DS was selling during those months when we were all making fun of it.
PSV has kept its head above water in the time since then, thanks to Golden Week, a string of holidays during which virtually every game system sees a sales increase (despite none of them getting new software). This year's Golden "Week" however was hardly a week at all, as most schools and businesses were open on Tuesday through Thursday. It ended up being more like a pair of consecutive three-day weekends. Therefore, its sales of 21k last week and 22k on the current report (week ending May 5) are not surprising.
But now is when things get tricky. There are no holidays coming until mid July, and the Vita won't get any new games until May 23rd, when Valhalla Knights 3 arrives. Moreover, that will be its one and only new game for the whole month of May. (BlazBlue is getting a budget-line version, but this does not count as a new game, and this title can already be found for cheap anyway.) Valhalla Knights is a successful series, especially in Japan, but it remains to be seen whether it can step up and move hardware. I expect its boost to be moderate at best.
It's with all of this in mind that I anticipate the Vita going below 20,000 units sold next week, and taking a step lower the week after that.
Will these predictions hold up? We'll be sure to let you know, and then make even more edumacated guesses. For now, we play the waiting game.