We should be "worried" and "fear" that we may be disqualified as teachers? Nonsense!
"Do you not know that those who run in a race all run, but only one receives the prize? Run in such a way that you may win. Everyone who competes in the games exercises self-control in all things. They then do it to receive a perishable wreath, but we an imperishable. Therefore I run in such a way, as not without aim; I box in such a way, as not beating the air; but I discipline my body and make it my slave, so that, after I have preached to others, I myself will not be disqualified." 1 Corinthians 9:24-27 (NASB)
What was at stake if Paul was "disqualified"? Not his position as a teacher or preacher, but from being disqualified from receiving the imperishable wreath! The imperishable wreath is not a teaching position. In 2 Timothy Paul writes: "I have fought the good fight, I have finished the course, I have kept the faith...." it was not about establishing teaching tenure at "Christian University" but "finishing the course by keeping the faith..." that "in the future there is laid up for me a crown of righteousness..." which is a requirement to enter heaven.
"[W]e are the children of God, and if children, heirs also, heirs of God and fellow heirs with Christ, if indeed we suffer with Him in order that we may also be glorified with Him." Romans 8:17. NASB.
"Fight the good fight of faith, lay hold on eternal life, whereunto thou art also called, and hast professed a good profession before many witnesses" 1 Timothy 6:12.
"For we are made partakers of Christ, if we hold the beginning of our confidence steadfast unto the end" Hebrews 3:14.
"Seeing then that we have a great high priest, that is passed into the heavens, Jesus the Son of God, let us hold fast our profession." Hebrews 4:14.
Disqualification is used in reference to salvation in several passages:
"Examine yourselves as to whether you are in the faith. Test yourselves. Do you not know yourselves, that Jesus Christ is in you?—unless indeed you are disqualified." 2 Cor. 13:5. NKJV.
"Just as Jannes and Jambres opposed Moses, so these men also oppose the truth, men corrupted in mind and disqualified regarding the faith." 2 Tim 3:8. ESV.
It is not like Paul limited "disqualification" to a position of teaching, but used it in reference to salvation elsewhere. All throughout Scripture is states the need to continue in the faith, the race, the fight, in order to receive eternal life, the crown of righteousness, salvation in the end.
"He who overcomes will inherit these things, and I will be his God and he will be My son." Rev. 21:7. NASB.