We prove that any finite energy geodesic ray with a finite Mabuchi slope is maximal in the sense of Berman-Boucksom-Jonsson, and reduce the proof of the uniform Yau-Tian-Donaldson conjecture for constant scalar curvature Kähler metrics to Boucksom-Jonsson's regularization conjecture about the convergence of non-Archimedean entropy functional. As further applications, we show that a uniform K-stability condition for model filtrations and the J K X -stability are both sufficient conditions for the existence of cscK metrics. The first condition is also conjectured to be necessary. Our arguments also produce a different proof of the toric uniform version of YTD conjecture for all polarized toric manifolds. Another result proved here is that the Mabuchi slope of a geodesic ray associated to a test configuration is equal to the non-Archimedean Mabuchi invariant.Conjecture 1.8 (Regularization Conjecture,[20]). For any φ ∈ E 1,NA (L), there exists a sequence {φ m } ⊂ H NA (L) converging to φ in the strong topology such that:Indeed, the results proved here can show that the conjecture 1.8 implies both Conjecture 1.5 and Conjecture 1.6, and hence also the uniform version of YTD conjecture (see Lemma 6.8 and Proposition 6.7). Although Conjecture 1.8 is not known in general yet, we can nevertheless use Boucksom-Jonsson's non-Archimedean approach to K-stability ([19, 20]) and Boucksom-Favre-Jonsson's foundational work on non-Archimedean Monge-Ampère equations ([14, 19, 20]) to get an existence result involving K-stability for model filtrations.To state a general existence statement, let G be a reductive complex Lie group in Aut(X, L) 0 with a maximal compact subgroup K such that K C = G. Let T = ((S 1 ) r ) C be the identity component of the center of