It couldn’t have been 2000 years later.
I agree the definition cannot mean some 2000 years later. But where do you find Scripture to support your opinion that 'shortly' or 'quickly' can be defined as around 40 years?
Here in the KJV of Scripture are the twelve places we find something defined as coming 'shortly'. Which of these verses support the opinion that what shall be 'shortly' shall come in around 40 years?
Ac 25:4 But Festus answered, that Paul should be kept at Caesarea, and that he himself would depart shortly thither.
Ro 16:20 And the God of peace shall bruise Satan under your feet shortly. The grace of our Lord Jesus Christ be with you. Amen.
1Co 4:19 But I will come to you shortly, if the Lord will, and will know, not the speech of them which are puffed up, but the power.
Php 2:19 But I trust in the Lord Jesus to send Timotheus shortly unto you, that I also may be of good comfort, when I know your state.
Php 2:24 But I trust in the Lord that I also myself shall come shortly.
1Ti 3:14 These things write I unto thee, hoping to come unto thee shortly:
2Ti 4:9 Do thy diligence to come shortly unto me:
Heb 13:23 Know ye that our brother Timothy is set at liberty; with whom, if he come shortly, I will see you.
2Pe 1:14 Knowing that shortly I must put off this my tabernacle, even as our Lord Jesus Christ hath shewed me.
3Jo 14 But I trust I shall shortly see thee, and we shall speak face to face. Peace be to thee. Our friends salute thee. Greet the friends by name.
Re 1:1 The Revelation of Jesus Christ, which God gave unto him, to shew unto his servants things which must shortly come to pass; and he sent and signified it by his angel unto his servant John:
Re 22:6 And he said unto me, These sayings are faithful and true: and the Lord God of the holy prophets sent his angel to shew unto his servants the things which must shortly be done.
Every usage of 'shortly' anticipates the things spoken would not be delayed, but expected with expedience. Scripture does not support your opinion that 'shortly' means some 30 to 40 years later anymore than it supports the opinion that 'shortly' means about 2000 years later. I don't believe you rightly understand what Scripture means when Christ says, "things which must shortly come to pass."
What about quickly? According to Strong's Greek Dictionary 'quickly' is the word Christ used to show His coming again will be without delay, once all has been made ready for His Second coming. IOW 'quickly' does not necessarily speak of immediacy of time as 'shortly' does, but rather unexpectedly, suddenly, when only those looking for Him to return will be able to discern His coming again in glory.
Strong's Greek Dictionary
5035. ταχύ tachy (tachý)
Search for G5035 in KJVSL; in KJV.
ταχύ tachý, takh-oo'
neuter singular of G5036 (as adverb); shortly, i.e. without delay, soon, or (by surprise) suddenly, or (by implication, of ease) readily:—lightly, quickly.
adverb
Since it is not 70 AD, nor is it 2000 plus years later, what does 'shortly' and 'quickly' point to coming immediately or within the first century of the Messianic Gospel age?