Of course eventually their end will come. The question is when. I think later rather than sooner. Here's why.
Apple are notable precisely for not falling victim to the Inventors dilemma. They have a history of being prepared to cannibalise their own markets and existing revenue streams. So, for example:
They switched entirely from PowerPC to Intel and didn't try to maintain a PowerPC line for the sake of backwards compatibility.
They launched the iPhone which cannibalised the iPod. They launched the iPad which they knew, if successful, would undercut MacBook sales (and has).
They released the MacBook Air at a lower price point than the MacBook Pro, knowing it was a superior solution for the majority of existing MacBook Pro users.
With hindsight it seems obvious they should have done these things because with hindsight it is obvious their strategy has lead them from strength to strength. However contrast with Microsoft to see how the innovators dilemma can have a real effect. Microsoft were not prepared to cannibalise Windows and now have a commercially under performing tablet/Windows frankenstein OS. They were not prepared to cannibalise Office so are hanging on to an outmoded business model where their feature advantage and user base is steadily being eroded. For the sake of avoiding disruption they have clung to the OOXML file format, which utilises highly normalised data (which doesn't work well for collaborative working because the data involves relationships criss crossing the whole of the document file and isn't isolated to a unit the user currently happens to be working in). And they are being undercut by ever more capable free offerings from Google and Apple, which, in both cases support collaboration (and have highly denormalised file formats). Sure they don't yet have feature parity, but especially where Apple iWork is concerned, the general structure of the UI is far simpler, easy to follow and more effective. Collaborative capability, and Web based access by any users go a long way to overturn Office dominance and many of the advanced features are becoming less and less relevant in this modern socially networked world where work is increasingly done in small collaborative chunks (often utilising focussed vertical apps on mobile devices rather than generalised Mallet to crack and egg solutions like Office), and utilisation of long Office documents is breaking down.
In truth a business Apple can be usefully compared with is Disney. Walt Disney instilled a set of principles in the company and most notably, instilled a quality ethic and the expectation they should drive for excellence. Those principles have stood the test of time (that's the thing about principles, they tend to be timeless, so do). Sure following Disney's death, it is no longer the company it was when he was alive. But the principles he instilled have helped it endure nevertheless. I think the world has yet to wake up to the fact inventiveness isn't required for those principles to be effective and stand the company in good stead. Because Apple are a secretive product company, the general public and analysts alike can't see where the next hit is coming from. But if you have a company occupying the space Apple occupy and hold on to ensuring principles, success will follow.
Pure inventiveness is the wrong measure. Invention has always stood on the shoulders of the giants who have come before anyway. Execute on principles organised around regard for user needs and priorities. Work hard to do that and sure as eggs are eggs,innovative products will follow. To corrupt a phrase, innovation is after all 1% inspiration, 99% perspiration.