NCAA release the list of hosting sites for the next 5 years
We hosting the West track and field regionals in 2021

Host for the Outdoor regionals are:
Date Championship Host(s) City State Venue
May 23-25, 2019 DI M&W Outdoor Track/Field Prelim Arkansas Fayetteville AR John McDonnell Field
May 23-25, 2019 DI M&W Outdoor Track/Field Prelim North Florida and Jacksonville Sports Council Jacksonville FL Hodges Stadium
May 28-30, 2020 DI M&W Outdoor Track/Field Prelim Kansas Lawrence KS Rock Chalk Park
May 28-30, 2020 DI M&W Outdoor Track/Field Prelim Kentucky Lexington KY UK Track & Field Complex
May 27-29, 2021 DI M&W Outdoor Track/Field Prelim Texas A&M College Station TX Texas A&M Outdoor Track and Field
May 27-29, 2021 DI M&W Outdoor Track/Field Prelim North Florida and Jacksonville Sports Council Jacksonville FL Hodges Stadium
May 26-28, 2022 DI M&W Outdoor Track/Field Prelim Indiana Bloomington IN Billy Hayes Track
May 26-28, 2022 DI M&W Outdoor Track/Field Prelim Sacramento State and Sacramento Sports Commission Sacramento CA Hornet Stadium

We are also hosting Regional Cross country in 2018 and 2020

http://www.ncaa.com/news/ncaa/article/2017-04-18/2019-2022-future-di-ncaa-championship-sites

Does this mean the track improvements will be completed?

We're also supposed to host outdoor SECs in 2020. I don't think we'd bid unless there was a reasonable chance that it gets built in time. Now, whether it's ready for the outdoor 2018 season like they said last year, that's a different story.