I'm eying for a GTX980. When can we expect the price to drop by about 20% due to new tech or something? Is this going to happen in the foreseeable future?

The Geforce 1000 series is coming out this year. Don't know what month. Expect prices to go then.

But I don't know why you'd go for the 980. 970 is a better bet for price per performance.

If you really want that extra 2GB of VRAM then get the 980 Ti. The 980 is in that kind of weird no-man's land between the 970 and 980 Ti and I really don't think the extra $200 price increase from the 970 justifies the extra 5 or 10 frames per second performance gain you'll get.

The cards along your upgrade path look as follows (ordered from lowest to highest tier):

AMD R9 290 - 4GB, good price/performance, lots of power and quite a bit of heat
Nvidia GTX 970 - 3.5GB + 0.5GB (slower), good price/performance, runs efficient and cool
AMD R9 290X - 4GB, good price/performance, lots of power and lots of heat
AMD R9 390 - 8GB, good price/performance, lots of power and a quite a bit of heat
AMD R9 390X - 8GB, good price/performance, lots of power but relatively cool
Nvidia 980 - 4GB, bad price/performance, runs efficient and cool
AMD Fury - 4GB HBM (new tech), bad price/performance, lots of power and quite a bit of heat
AMD Fury X - 8GB HBM (new tech), average price/performance, lots of power and heat but liquid cooling comes standard
Nvidia 980 Ti - 6GB, average price/performance, quite a bit of power but efficient
Nvidia Titan X - 12GB, bad price/performance, lots of power and quite a bit of heat

Price/Performance remarks are based on the going rates in the US.

Generally if you don't have heat/power concerns, the GTX 970 is avoided due to the "not truly 4GB VRAM" debacle. The 290X and 390 perform quite similarly, but the 390 is more efficient and is generally the same price or cheaper nowadays. The 980 only barely edges ahead of the 390X in terms of performance, but it is much more expensive, which makes it not a great pick most of the time (as an aside: I actually have a GTX 980 because of power constraints). The Fury beats the 980, though not by much, and there is once again a large price hike. The Fury X and 980 Ti are pretty comparable in both price and performance, but the 980 Ti comes ahead in many titles, which is compounded by its superior efficiency. Finally, the Titan X is more powerful than the 980 Ti, but the price premium on it makes it more of a novelty than an actual consideration.

Therefore, the general upgrade path I'd consider for high-end cards is 290 -> 390 -> 390X -> 980 Ti. You can do your own research for any of the cards mentioned above (or look at previous generations if you're able to find any) if you think they fit the bill better, though.

A GTX970 seems like a comparably small step up considering it still costs over $300.

A 970 Ti seems to fit that gap but unfortunately there's no such card. Are there other alternatives?

Anything more specific on how long I'd have to wait or if it's even going to be worth it?

It's not really a small step. It's a solid 1080p card.

The 780 Ti would fit the bill, though there are not many reasons to choose it over the 970. While it's better in terms of specs, the Maxwell architecture brings optimizations that Kepler lacks.

AMD has the 390X, which uses more power but actually runs cooler than the 980 (according to Anandtech). It also has more VRAM.

For what it's worth, I picked up a B-Stock 980 on EVGA's site for $375, though I don't know if that's an option for you.