There's nothing wrong with system. This is very stable. But there are things that are in constant change. For example when there is new version of PHP with major changes, then TB will not work. And this new PHP is coming sooner or later. Also all kind updates in modules. Now, if you have let's say 1000 client, 10 000 different item (combinations or whatever) and who knows how many modules to make your shop working then it is a lot more than PITA to make all this work on somewhere else. For me there will be also need to translate, find out what is new, there are lot of situation when the same thing is with different name, but this will take time to understand this, etc. Shortly, this migration is anyway nightmare and this will be more sickening if you need do this fast. But, If You are smart then you think about this, you make plan B and you don't count on miracle that somehow all this will be working itself or there is configuration that lasts forever. At the moment there is something like 18 months when nobody knows how or where this project is going. So if You need that your shop is working then you move to someplace else. Yes, maybe You can fix all things in Your shop, but this doesn't mean that all can do this. Bad thing is that if someone already makes decision to move on some other software, then it will be hard to convince to move back. But hey, only 3 more days to wait, or to be honest to the end of this week.