Localized and regional leagues are a great initiative. It would give established players much choices and new players much chances. Players move around the globe to play where they love and where they are loved. With every league having a minimum number of local players, the new players gets a chance to play with more experienced players from around the world. These leagues are not exactly a challenge to IPL but a platform that could bring new and talented players to IPL.
I like the idea of BPL, because the BCB started it off as a low-profile tournament and they never tried to challenge the established leagues such as the IPL and BBL. They were aware of their financial situation and made sure that the franchises and the organizers don't incur heavy losses. And that's why the BPL became a success and the SLPL became such an outright failure.
In case of SLPL, one of the mistakes they did was they expected the league to have good viewership from the global audience. That never happened. If you want to attract global audience, then you need the T20 heavyweights, such as Virat Kohli, Rohit Sharma, Pollard, Russell, Gayle, Warner, Maxwell.etc.