A swap would be very likely imo. Roi Yim and Sabai are both essentially surplus to the region already, and both would be of great use to the US population.
Sabai especially, being just one of two surviving offspring to his two wild born parents; his brother of course though being the breeding bull at Werribee. Roi is the nephew of Ongard, but considering the size of the US population, they could do with breeding from both bulls.
Any of the young bulls now would be very good candidates for a trade in a decade or two down the line. You mention the young Texas born bulls - but there's countless that could be options.
Imo getting even Sabai into the region would be immensely beneficial for both regions. If a bull isn't needed straight away, then space is now open at Dubbo for another bull, bull calves, etc. Sabai would be a perfect fit for Miami to join Ongard as well. Despite their exhibit being far from top-tier, they do have capacity for an additional animal and I'm sure both bulls would thrive with each other's company.
As for hypothetical exports down the line, I went a head and looked at bulls that will be under the age of 20 in about a decade (and of those, ones realistically options to export in connection to the worldwide breeding program), which leaves:
- 1.0 Kabir (Upali x SheRa) 2017.05.15
- 1.0 Sanjay (Upali x Anak) 2018.02.10
- 1.0 Onyx (Johnson × Opal) 2018.08.18
- 1.0 Nelson (Thailand × Shanti) 2020.05.12
- 1.0 Teddy (Thailand × Tess) 2021.05.16
- 1.0 Frankie (Hank × Phoebe) 2021.06.16
- 1.0 Brazos (Romeo × Bluebonnet) 2021.10.21
- 1.0 Yaad (Doc × Mali) 2022.10.24
- 1.0 Tukada (Doc × Mali) 2022.10.24
- 1.0 Travis (Romeo x Belle) 2023.02.23
- 1.0 Jet (Jake x Jade) 2024.11.23
- 1.0 Xerxes (Bowie x Achara) 2025.06.16
- 1.0 Unnamed (Sabu x Phoebe) 2025.10.21
The most realistic options imo would be Nelson, the Fort Worth boys, potentially the twins, Jet and Xerxes.