The main conjecture on degree-\a0$k+1$ vertices in minimal $k$-extendable bipartite graphs

Let $G$ be a minimal $k$-extendable bipartite graph, with $k\geqslant 1$, order $n$, and size $m=|E(G)|$. Let $V_{k+1}$ be the set of vertices of degree precisely $k+1$. Main conjecture.

$$|V_{k+1}|\geqslant \frac{2}{2k-1}(m-n+2k).$$

This conjecture is proposed as a strengthening of Lou's lower bound in terms of the order and size; its status is not resolved in the supplied text.