In short, the section from the Texas state line to US 171 will not be built during my lifetime. Good. The whole diagonal across Louisiana and Arkansas seems rather pointless.
Or...just do as I originally recommended and dump I-69 between Carthage and Monticello and reroute through US 425/US 165 to I-10 E of Lake Charles, and use the US 59 corridor to Texarkana for the Texas segments.It does seem like it would be much more economical and time-efficient to expand upon TxDOT's current efforts to upgrade existing roads for I-69 and use Anthony's similar notion for Louisiana and Arkansas up to Monticello. Maybe keep the portion of SIU 15 that would complete the Shreveport Inner Loop.
I've always thought that it would be better to simply split the proposed I-69 extension into three elements:
-- The US 59 upgrade between Laredo and Texarkana (possibly as I-41 or I-47), with US 77 from Corpus Christi to Brownsville upgraded as an extension of I-37 (the remaining segment of existing I-37 to CC would become an I-x37 connector, while the segments of SH 44 and US 77 connecting with US 59 could be upgraded as standalone freeways (or as I-x41/I-x47)).
-- An upgraded US 165/US 425 corridor from Lake Charles through Alexandria, Monroe, Bastrop, and Monticello (my proposed I-51) that would then branch off into two branches: one would continue along present I-530 to Little Rock, then extend NW along I-40 and US 65 through Conway, Mountain Home, Branson, Springfield, and then NW'rd to connect with Future I-49/US 71 near Kansas City; the other would be the truncated I-69 extension to Memphis. (I'd save I-53 for the US 67 freeway, which would be extended as planned to Popular Bluff, MO, then to Festus, then cosigned with I-55 to the outskirts of St. Louis, then connected with US 61 to a freewayized Avenue of the Saints all the way to just south of Minneapolis-St. Paul.)
-- And, the third branch would be the proposed I-69 extension from Memphis to Indy, which would remain as planned.
'Course, I'm a bit biased in this, since I've been pushing for a Lake Charles/Alex/Monroe/Monticello freeway for the longest.