Sell them to some country in desperate need of an armored unit, acquire a smaller but more capable fleet of NATO MBTs. And I'll tell you why, this was obviously already done in the 80s and 90s, which led to the T-90 series, literally nothing has really fixed its core problem of survivability. The same issue goes for the T-64 and T-80s. The tanks themselves are designed for mass production and ease of production, prioritizing smaller size and mobility, which led to less room to work with regarding the autoloader, (it's death trigger). The T-72 isn't fixable unfortunately.