Understand how fragile a 4.0 GPA is as credits accumulate, what a single lower grade costs, and calculate whether a perfect GPA is still reachable.
It can make a literal 4.0 mathematically impossible for that term or cumulatively, since 4.0 is the scale's maximum and there's no higher grade to offset it. How much it affects your overall standing depends on your total credit count.
Yes — each additional credit at a lower grade needs proportionally more perfect-grade credits to fully offset it as your total credit count grows.
If retakes are allowed and your institution's policy replaces the old grade, a retake can restore eligibility; otherwise a literal 4.0 cumulative typically isn't recoverable once a lower grade is permanently recorded. Check your Retake Calculator scenario and official policy.