You mention in your question that outside forces are preventing you from writing (I'm guessing fast enough?) but I'm that kind of annoying person that believes there's always a solution out there, so I'll write (at length) about that. However, at the end of my answer I'll also talk about ways to get your thoughts out there even if you cannot write that much. So you can always skim to the end... ;o)
Look at it from outside the box
To me, death is the great motivator.
I think, if humans lived forever, I'd be the kind of person that spent forever preparing. Only the awareness that I have limited time pushes me from preparing to doing.
This, to be, in some strange way, thankful that I have a limited life, is probably very strange to most people. But being, what I call eccentric (oh well, yeah there are some diagnoses there as well), makes it possible for me to look at the world from outside the box. (I pretty much have to strain to figure out what's going on inside the box...)
I'm also clinically positive about life (for instance I believe that death isn't the end, of my existence, but for sure the end of this very unique experience called my life, so I'd better carpe diem the crap out of it, but without that much angst about it... if that even makes sense...)
With outside-the-box thinking and positivity, I often find myself thinking about how a problem can be a good thing or a help. A bit like if you give me lemons, I'll bring the tequila... :P (Oh wait, alcohol is very seldom the solution to any problem... let's stick with lemonade instead!)
Can you learn to be positive? I don't know... I do, however, know that this positivity is something that came after many years of far less positive, even negative, thinking, so I wouldn't rule it out. And no, it isn't "just happening" it takes hard work and time... (and about half a meter of self-help books) and possibly a notion that all that sh*t is part of the process/experience... that without it I wouldn't be "here", I wouldn't be me. Maybe I'd be superficial and pointless!
You're still writing a book
But even with positivity and outside-the-box thinking, normal rules for creativity and writing apply.
Sometimes you get stuck. Sometimes your ability or time puts limits on what you can create. It could be disabilities, children, lack of planning, too much coffee with friends. Pretty much anything can prevent you from creating.
Some problems can be solved. Some problems will be part of your creative landscape and things you just have to learn to work with.
One possible solution could be to apply acceptance to problems going on "in your head." This works especially well for unwanted thoughts (since "you cannot not think"). Instead, you work at doing the things you want with your life while you have the thoughts telling you it's impossible... Sooner or later those thoughts will stop pestering you... as long as you don't try to make them stop... (the mind is a weird thing...)
If you want to learn more about acceptance and thoughts etc, I recommend reading "Get Out of Your Mind and Into Your Life" by Steven C. Hayes and Spencer Smith. It helped me immensely.
Getting your thoughts out there
You're asking about how to handle the possibility of not finishing the novel before your time runs out.
The first step is to work on the novel and let the problem of death be something that may or may not be relevant for this novel. If you have your last will and testament in order, I think you can just accept that death is there and you will or won't finish the novel.
If you work on a series, each novel needs to stand on its own legs anyway so even then it's about writing one book at a time.
Find a long-term strategy where all important parts of your life get a practical amount of attention (health, family, friends, work, writing, etc).
That's pretty much what I'd recommend with or without writing.
But if you really want to make sure your work gets out there, for instance, if you start an epic series, you could always create outlines and world-building data that could make it possible for someone else to finish the work. It wouldn't be the first time even if it isn't necessarily the best of strategies either...
If writing really is what you need to be happy/feel meaningful etc, then write and let the novel be a possible result of that writing. The long-term strategy should definitely be based around the fact that you like to write, be that in NaNoWriMo-speed or one sentence per day.
Maybe all you can muster is haiku poetry on your blog. It's still writing and it's published. Putting anything out there is way better than just planing to do it. Even if it's a small text, it's going to be one rung in the ladder towards feeling like you can actually write and publish something.
It would be your answer to the thoughts that say you will never be able to publish anything in time... (And here's my version of that type of blogging, although in my case it's more of a dumping ground for thoughts and ideas. But those thoughts and ideas are out there, and public...)