Here are the facts
1. She has won every single race she has entered in the 800m and 1500m this year and this is the first year she has ever entered races recognized by world athletics.
2. She has yet to run internationally. She has only run in Australia.
3. This is her progression against Australian runners this year (she only ran highschool comps before this year)
Feb 1:59.8 win
March 1:58.8 win
April 1:58.4 win
This is her progression in the 1500m
Feb 4:04.45 win
April 4:02.96 win by over 10 seconds
I'm not saying she is likely to medal. She definitely has no experience needing to put rounds of 2:00 and 1:58 together just to make a final, so that is an unknown.
I'd say we'd expect 1:58 low to 1:57 high if we got her in an international field right now. I also think this indicates she is in sub 4:00 shape. Making the final would indeed be a good result. If she continues this progression though, her PB will be in the 1:57s by the end of the year. That I'd definitely bet on.