For over a decade, high-end graphics cards have been taking up at least two slots, and in recent years even mid-range cards have gotten wider. According to Videocardz, XFX might have some RX 460s that buck that trend. The single-slot coolers on the purported Radeon RX 460 Core Edition cards are sharp-looking, with a clean design that recalls the Radeon Pro WX series.
Assuming Videocardz's info is correct, the two incoming cards are identical aside from your choice of 2GB or 4GB of memory. The base clock rates on both memory and GPU core match AMD's reference numbers: 1090MHz for the GPU, and 7 GT/s for the memory. XFX adds 20MHz to the boost clock, however, for a total of 1220 MHz. The cards will offer a dual-link DVI connection, an HDMI port, and a DisplayPort jack.
There's no official word from XFX yet and the cards have only just appeared in Videocardz's database, so we don't know anything about pricing or a release date. Given their compact size and slot-powered nature, one of these could make a potent upgrade for a pre-built or compact PC.