Peace,
Here is the issue as I see it. The Quran is not outdated but we have been looking at this all wrong. The Quran used words like Ramadaan, Kaabah, Mecca and Bakka and Holy months beinig ma'loomat, ahillat knowing that the Arabs at the time or those focus on their practices could either choose the universal application of the Quran. The Quran says that it also lead astray but it only leads astray those who have wrong in their heart. Most of the Arabs of Muhammad's day had wrong in their heart so they opted for the meanings of word like Makkah and Kaabah that confirmed their Arab traditions. But this was wrong.
In accordanc with the Old Arabic language that the Quran is written in:
Ramadaan = Season or lasting time of Heat
shah-r = 30 days
Ka'bat = true honor/glory
Makkat= true destruction
Bakkat= High rank, a cut above the rest, distinguished, crowding
Ahillat= Things that are selected to be consecrated
Ma'loomat= tu'lamu= "is to be (should be) dinstinguished, well known, discerned"
So if we put all the pieces together we don't need the old Arabic calendar. Because during the hot seasons in any place that we may be we are to fast for 30 days.
"God, with true glory(al-ka'bata) will make sacred houses (sanctuaries: Al-baitul-haraamu) an upliftment for mankind" 5:97
"They will ask you about about the consecrations (ahillatun, from haleel, from maa uhilla:). Say: They are to be timed (mawaaqeet from mawqoot) for the benefit of the people" 2:189
The consecrations are to be timed for the people and not at random during the Hajj, and instead of that whole entering through the back doors thing that verse can be understood as 'By the pilgrimage! Righteousness isn't entering the houses of God just to make your appearences there(bi'an ta'too al-buyoota bidhuhoorihaa). The righteous individual is the one who is worried about his well-being (attaqaa). So go through the doors of these houses (al-buyoota) and worry about God so that you can succeed." 2:189
"The season(s) of pilgrimage should be (are to be) months that will (are to) be well-known, distinguished, discernable" 2:197 That means we can chose them, and that we should make them clear and widely known.
"The count of 30 day periods as far as God is concerned is to be 12. This was his decree the day he made the heavens and the earth. Four of them should be (are to be) sacred, and that will be (is to be) how it stands. (the standing order/rule)." 9:36
"And when you are fully vulnerable (bi batni makkata), it is God who would hold you back from them and them back from, discounting the possiblity that he may empower you so that you can defeat them." 48:24
(There are times when both sides are on edge and damages may be fatal to both sides, but it is God through his book and through his divine will that keeps those tentative times of peace)
Taking all this into account the Arabs could have understood Makkah ehre as the city and The Ka'bah as the Holy shrine in Mecca. They could have, with reason, kept the traditional months (which unkoranically they understood as the moon phases) of pilgrimage as they were widely known.
And they could have grammatical and through their unkoranic understanding continued to understand ahillat as moon phases. But with linguistic analysis and analyzing the Quran they didn't have to. And here is an alternative understanding.
Godlbess,
Anwar