1964 was the last year for coinage of 90% silver dimes, quarters & half dollars

Only if you are just counting silver circulated coins. They still produce silver dimes, quarters, half dollars, and dollars every year. Most are for proof sets, though some brilliant-uncirculated are also available.

Technically you are correct though, because of the percentage at least. The silver dimes/quarters/half-dollars (and of course the dollars) being minted are 99.9% silver.

That reminds me - I need to remember to get a silver 2026 dollar and half-dollar next year to go with my 1976 Bicentennial silver proofs.