For that area, I could see them using the existing interchange, then veering to the west on new alignment north of the interchange area, and still bypassing the town.
They couldn't just re-build the US-69/US-412 interchange as a run of the mill cloverleaf. But a cloverleaf seems likely given ODOT's habits. There would be serious merging conflict issues if there was a cloverleaf interchange and then a "Y" interchange within a close distance of each other. ODOT would have to design a more creative solution to veer the US-69 main lanes at an angle thru the interchange to bend traffic flow into the direction of a new bypass.
As far as I know, the I-45 extension would only be up to 412, hence the interchange redesign.
It would be a wasted effort if an extension of I-45 into Oklahoma ended unceremoniously at US-412. I could imagine a phase of an I-45 extension ending there for a certain amount of time.
The enormous amount of heavy truck traffic coming up from the DFW area is not going to hang a left or right on US-412. It's going to keep heading North to Big Cabin just like it's doing right now.
That's a lot of bypasses on that route and those towns do not want the highway upgraded. That's why it would make more sense to route I-45 to Tulsa on the Indian Nations Turnpike north of McAlester and onto US-75.
ODOT does not have to build bypasses within the city limits of any towns along US-69. Considering the pretty crooked bend US-69 takes going into the South side of Muskogee it would be pretty easy for ODOT to build a new terrain freeway bypass West of Muskogee and not put traffic way out of its way. Wagoner would be even easier to bypass to the West.
Then there is the safety aspect. It's not exactly a good thing to have lots of semi trucks pounding down the main surface street in a town. Then there's all the noise from trucks as well as the wear and tear on local streets. Most towns outside of the OKC and Tulsa areas are slowly losing population. A new Interstate might help spur at least some economic development and reverse some of the exodus.
Upgrading US-75 from McAlester to Tulsa to Interstate standards would be a good idea. But doing so would not be any easier than upgrading US-69. It might even be more difficult. As you mentioned, Okmulgee is a serious obstacle. Henrietta is a bit tricky too. Between Okmulgee and Glenpool US-75 has quite a few properties encroaching too close to the highway to incorporate frontage roads and/or exit ramps.
I agree that US-69 should be improved and that those towns should not have all that truck traffic running through the centers of those towns, that was my point with Okmulgee, which is larger than those towns on US-69 north of Muskogee.
My point about the US-75 route over US-69 is that the US-75 improvements are going to happen no matter what and when US-75 south of Tulsa is improved it will pull traffic from US-69 as an easier way to get to I-44. That said, the no growth thing doesn’t apply to the US-69 corridor either.
Muskogee is losing people and I don’t see that changing, but Wagoner, Chouteau and Pryor? Wagoner and Inola are seeing suburban growth now. Pryor and Inola are about to explode in population and will likely take Chouteau with them.
MidAmerica industrial park in Pryor already has a number of big business including Google’s largest data center. Panasonic is bringing 4,000 new job there soon and Canoo if it survives the electric car wars might bring a few thousand more. The Tulsa Port of Inola recently opened a big plant for Sofidel and just announced 1,000 new jobs for Enel making solar panels. Those are just the big projects coming and there are big plans to expand both industrial parks, especially the one in Inola since it has a port and is closer to Tulsa.
That’s going to add 6-7,000 new jobs at least in the next 3-4 years to Inola and Pryor.
Maybe all the growth will force the state to upgrade US-69 eventually, but both industrial parks are also adjacent to US-412, which is where the state is putting money into upgrades now. The idea is that this future interstate US-412 between Tulsa and NW Arkansas will be a green industry corridor linking both metros.