The NBA has flirted with the idea of expansion teams for several years. The move feels inevitable as the league's revenue continues to skyrocket. If it adds teams beyond the current 30, a popular choice has been to bring back the Seattle Supersonics.
The Sonics relocated to OKC in 2008. The controversial decision resulted in a complete rebrand to the Oklahoma City Thunder. Despite most people treating both iterations as separate franchises, the Thunder technically owns the Sonics' history.
It's viewed as the same franchise by the league but that's about it. The Thunder have distanced themselves from the Sonics, but there's a reason why nobody in OKC has worn any of Seattle's retired numbers.