There's hope, since Microsoft has expressed an intention to support the high-resolution capabilities of the Lumia 1020 in succeeding Windows 10 Mobile builds. In fact, there's a thread (I can't find it now) where a user reports being able to download Lumia Camera for his Lumia 1020 in Windows 10 Mobile, but since I don't have any intention of upgrading my L1020 now I can't confirm that.
Our friend, Steve Adams, might report back with his findings comparing Windows Phone 8.1 and Windows 10 Mobile TP (current version?) - hopefully it'll have the same high-resolution images for both OS versions.
Nonetheless, a Lumia 1020 running Windows Phone 8.1 should still be worth keeping, with the idea of maximizing stability and the high-resolution sensor - at the moment at least.