There are still numbers left. We could see a 3040 built if there was actually a market for one. The question is would it be fast enough over an integrated GPU / APU to get people to buy one?
One of the primary markets for lower end cards used to be OEM machines. When they sold those cards by the millions in Dell and HPs for businesses there was plenty of reason to make the card. Most of the OEMs I see now don't have discrete graphics, so the volume they've been selling those cards at has likely tanked over the past few years.
That said just looking at this card you see there is only one GA107 card. They could likely do a cut GA107-200 if they are already making those parts, so it does seem like there is a chance to see an RTX 3040. The thing that I've been saying since this series released is they had to make room for more numbers at the top, so they pushed everything down. The 3060Ti is really a 3070, so that would also lend to them making another card that slots below a xx50 card in this generation.
we effectively did have a 2040 last time around. If they hadn't bifurcated the product line into 20xx and 16xx subfamilies, the 1660 would have been the 2050, and the 1650 the 2040.