What is the solubility of ionic solutes in water?
We don't know. You have to assess solubility on an individual basis.
Water is a solvent that is capable of solvating many ions and molecules. On the other hand, ionic solids are species that generally have very strong INTRAMOLECULAR forces of attraction. Ionic solids are thus non-molecular species in which every particle interacts, attractively or repulsively, with every other particles in the ionic lattice.
Many ionic species have some considerable water solubility in that they are capable of forming solvated ion complexes:
Other ionic species have such strong electrostatic attraction between particles that they are essentially insoluble in water, and do not undergo this reaction. Of course molecular substances may not have the same water solubility, especially if they are incapable of hydrogen bonding. Nevertheless, simple covalently bound gases, dioxygen and dinitrogen, have water solubility.