Up to what date will the college student discount be available?

In US, the student deal ends on September 26, 2019. https://www.apple.com/promo/pdf/EN_US_BTS_FY19_TandCs.pdf

Those eligible to purchase from the Apple Store for Education Individuals include faculty, staff, students and parents as follows:

• K12 - Any employee of a public or private K-12 institution in the United States is eligible, including homeschool teachers. In addition, school board members who are currently serving as elected or appointed members are eligible. PTA or PTO executives currently serving as elected or appointed officers are eligible.
• Higher Education - Faculty and staff of Higher Education institutions in the United States; and students attending, or accepted into a Higher Education institution in the United States are eligible to purchase. Purchases from the Apple Store for Education Individuals are not for institutional purchase or resale.
• Higher Education Parents - Parents purchasing on behalf of their child, who is a student currently attending or accepted into a public or private Higher Education Institution in the United States, are eligible to purchase.

Retrieved from Sales Policies - Education - Apple

Back to School - Student Discounts - Education - Apple

Hope that helps.

Patricia