The opportunity with Loyd staying was an NC. That opportunity was lost so necessity forced a change. The opportunity with a healthy Turner was making the final 4. If she's done then necessity forces a change that probably does not include a final 4.
Besides all that, the number of games left for ND in this tournament is not going to have as much effect as you are postulating in building some kind of core. That is done as players mature through time and over a season. Next year without Allen the team chemistry will be different and the core will have to form out of those new circumstances.
Losing Turner would suck and not be anymore of an opportunity than losing Achonwa was.