Does that verse mean that every local church ever built will endure to the end? I don't believe it does. There will always be a church, but, sadly, plenty of local churches have met their end.
Or do we allegorize the Ottoman beylik that conquered Asia Minor as the gates of hell?
I believe it means exactly what it says,
But I would not have you to be ignorant, brethren, concerning
them which are asleep, that ye sorrow not, even as others which have no hope. For if we believe that Jesus died and rose again, even so
them also which sleep in Jesus will God bring with him.
For this we say unto you by the word of the Lord, that
we which are alive and remain unto the coming of the Lord shall not prevent
them which are asleep. For the Lord himself shall descend from heaven with a shout, with the voice of the archangel, and with the trump of God: and
the dead in Christ shall rise first: Then
we which are alive and remain shall be caught up together with them in the clouds, to meet the Lord in the air: and so shall we ever be with the Lord.
I believe those underlined and those in bold are both in the church of Matt 16:18 with the ones underlined having passed through the gates of Hades.
Now this I say, brethren, that flesh and blood cannot inherit the kingdom of God; neither doth corruption inherit incorruption. Behold, I shew you a mystery; We shall not all sleep, but we shall all be changed,
I believe those of 1 Cor 15:50,51 are the same, of the church of Matt 16 and of those of 1 Thes 4:13-17
Thus the statement V 55 where, O Death, thy sting? where, O Hades, thy victory?'