  In the main part of the paper we project forward to having $B$ factory
determinations of $\sin(2\beta)$ and $\sin(2\alpha)$, for which we take several
values. First, we use a joint $\chi^2$ analysis of CKM experiments to constrain
CKM matrix elements in the standard model, and experiments on the angles
$\alpha$, $\beta$, and $\gamma$, and on $x_s$ and null $CP$ asymmetries. Then
we invoke mixing to a new isosinglet down quark (as in E$_6$) which induces
FCNC that allow a $Z^0$ mediated contribution to $B-\bar B$ mixing and which
brings in new phases. We then repeat the $\chi^2$ analysis, now including
experimental constraints from FCNC as well, finding much larger ranges of
prediction for the $B$ factory. We then add projected $B$ factory results on
$\sin(2\beta)$ and $\sin(2\alpha)$ and repeat both analyses. In $(\rho,\eta)$
and $(x_s,\sin{(\gamma)})$ plots for the extra isosinglet down quark model, we
find multiple regions that will require experiments on $\sin{(\gamma)}$ and/or
$x_s$ to decide between and possibly to effectively bound out the extra down
quark contribution.
