Scott, let me try to respond, but please understand that this is an opinion from down here in New Mexico, and what matters more is how the Colorado AG's office views the state's obligations under the C&TSRR Compact. On the other hand, we have had legal experts in NM review the terms of the Compact, including a lawyer who practices before the U.S. Supreme Court on interstate compact issues.
What we have learned is that the legal precedents are clear that a state cannot unilaterally alter the terms of a duly executed compact with another soverign state, even by arguing that a state constitutional amendment, such as TABOR, prevents the state from allocating funds to the Compact. The terms of the compact take precedence.
If so, Colorado ought to find a way to allocate funds to the C&TS on what is catergorized as a "TABOR Exempt" basis (see the Colorado Long Bill for examples). Remember, under TABOR Colorado actually is running a surplus, and that surplus is what is returned to taxpayers. Funds for the C&TS could come out of that surplus, which I've been told by Coloradoans amounts to hundreds of millions of dollars.
So, if this logic is correct, the C&TS might actually be better off if Proposition C fails since it would not be competing for funds with other un-met needs (such as buildings for higher education.
The bottom line is that what is needed is political will, and that's up to the folks in Colorado.