No, you won't loose access, or at least it's incredibly unlikely you will. DDB has never taken away content from people that they own to date. Two things will happen

1. Most likely (90% chance imo) - the 2014 Bladesinger will be tagged as legacy and you will still have access to it, but only on 2014 Wizard. This is the same as for example the evocation subclass. If you want it on the 2024 wizard, you'll need to make a homebrew copy.
2. Least likely (30% chance imo) - the 2014 Bladesinger will be tagged as legacy but will remain useable on the 2024 wizard along side the 2024 Bladesinger
3. Almost impossible but mentioning for the sake of completionism (<1% chance imo) - the 2014 Badesinger will be updated to match the 2024 Bladesinger

I'm assuming you mistyped one of those probabilities.

I do hope they won't go with option 1, as that would brake existing characters. That's a big difference to evocation - there were never any 2024 wizards with the 2014 evocation subclass, so disallowing the combination didn't affect any previously made characters.

I still have quite a few old UA PCs that still exist after they released the official version. That seems to support Davyd's option 1 for new PCs, and existing 2024 Wizard PCs with a 2014 subclass you have made will still be usable. You simply won't be able to make new ones like that. 

An important note on the likely behavior -- if you change the subclass off 2014 bladsinger on a 24 character, you probably won't be able to get it back.

The big difference between Bladesinging and Evocation (aside from the timeline), is that the updated Evoker is included in the Free Basic Rules.
It doesn't matter (as much) that we can't use Evocation, because we can all use Evoker instead.
But if we lose Bladesinging, then they're basically forcing us to buy the new book to play a subclass that we already own.
We've all seen some scummy things from Hasbro/WotC, but that would certainly be a contender.

You are not required to buy the new Bladesinger if you want to play the old. You don't even need to resign yourself to only using the 2014 class to enjoy the 2014 Bladesinger. Just homebrew it like dozens of people have already done with their preferred 2014 subclasses. You can find several examples on the Homebrew page. This isn't even remotely scummy because they give you all the resources you need to keep using the old content and allow you to use it on the new class you seemingly like.