I can think of only 2 effects that is
- The Induced Dag would Reduce with increasing AR of wing. This goes by the simple formula:
$$ C_{d(i)} = \frac{K \times C_l^2}{\pi \times \text{AR}} $$
As drag decreases as AR increases & lift also decreases as AR increases, so the Aerodynamic Performance (L/D) decreases. To check this we can use another simple formula:
L= Cl*1/2*ρ*V^(2)*S &,Cl α 1/(AR)
But what are other effects of increasing AR (including Structural & Aeroelastic Effects)?
Also One can correct me if they feel I am wrong.