Doesn't TB2 have two interleaved streams, one carrying DP1.2 and the other carrying 20Gbps PCI-E? Even if the PCI-E stream has enough bandwidth for 5K in theory

Doesn't TB2 have two interleaved streams, one carrying DP1.2 and the other carrying 20Gbps PCI-E? Even if the PCI-E stream has enough bandwidth for 5K in theory, the ecosystem isn't in place to use it as a display output. That's what the DP part is for.