That means Texas Instruments no longer manufactures it, and no last-time-buy window is open.
Replacement planning
The DS90LV031 family includes active variants — the DS90LV031ATMTC (non-tape-and-reel) and the DS90LV031ATMX (different package) — but those are also obsolete or limited. A practical replacement candidate is the DS90LV032A (quad receiver) if you need the opposite function, or a newer-generation LVDS quad driver such as the DS90LV047A (also 400Mbps, 16-TSSOP). Pin compatibility is not guaranteed without a datasheet cross-check, so verify the footprint and electrical interface before swapping.
Key specs for the design-in check
The DS90LV031ATMTCX provides four differential driver channels with a typical output voltage swing of 350 mV into a 100-ohm load. The 400Mbps data rate per channel supports LVDS signaling for high-speed clock distribution or serial data links up to several meters over twisted-pair or PCB traces. The 16-TSSOP package has a 4.40mm body width and 0.65mm pitch — a common footprint shared with other LVDS quad drivers, which simplifies board layout if you need to swap in an alternate later.