A Texas representative is attempting to amend federal I-69 legislation to allow designation of portions of defined corridor that are currently up to interstate standards to be signed as I-69, even though those portions do not currently connect to another interstate: http://www.themonitor.com/articles/interstate-44356-designation-valley.html
"A slight tweak to language included in the 1995 law that designated U.S. 77 and U.S. 281 as future segments of the interstate highway system could be a step toward securing the long-awaited blue shield for the two Rio Grande Valley highways ... Although the National Highway System Designation Act of 1995 stipulated that the two north-south highways leaving the Valley would be included as part of the I-69 corridor, it also said that they must be up to interstate system design standards and connect to an existing interstate system ... By adding language to the federal code that allows those sections because they connect to the border, the Valley could already reap the economic benefits of an interstate ..."
Looks like he will attempt to amend the law to make a border terminus the equivalent of a connection to another interstate.
TxDOT's website now has pdfs of Nov. 2010 Interim Reports from the five I-69 Segment Committees: http://www.txdot.gov/public_involvement/committees/i69/default.htm
In these reports, the respective committees identify the interim top 5 priorities for each Segment (Segment Committee 4, in an attempt to not favor either US 77 corridor over US 281 corridor or vice versa, list top 4 separate priorities for US 77 and US 281 corridors).
The Committees also recommend immediately signing the following freeway sections as I-69:
Committee 2: US 59 in Houston from I-10 northward to Cleveland;
Committee 3: US 59 in Houston from I-10 southward to Rosenberg;
Committee 4: US 77 from I-37 to south of Robstown; US 281 from Mexican border to north of McAllen; US 77 from Mexican border to south of Lyford.
The first three recommendations are analogous to the Mississippi segment of I-69 because they tie in to current interstates. Apparently, the final two would be dependent upon the proposed legislation that would make a terminus at the Mexican border equivalent to an interstate junction.