yup...
exo exploration and colonisation is costly, dangerous, with a very low chance of success..
and takes more time than I think we have to accomplish...

endo exploration however ...is more cost / resource effective, with a lower chance of risk, and a higher chance of success given the time we have and the speed at which we deplete resources ...

even as we come up with more efficient ways of consumption and conservation, even as we come up with better and better alternatives..
it is still an uphill battle we are facing in regard to our hungry demand...

for example...
lets say we have at most and best we have 100 to 200 years maximum...
before all our consumable resources are depleted at current and anticipated demands...

-factor in advancements to conserve and more efficiently utilise these resources...buying us a little more time...

-factor in breakthroughs and new technologies that are discovered, and then implemented to offset or replace SOME of our consumables...

-factor in the great need to utilise the ever dwindling consumables TO work at attempting to escape them...most likely only in part..
this will hamper advancement..
(For example ...these "new" breakthroughs anticipated...even existing alternatives such as solar or wind power, geo-thermal wave action on the ocean...How exactly have they been manufactured? right down to each part...right up to distribution...the chain of "need " for their creation, distribution, parts, repair and maintenance IS dependant on petroleum...as the supply becomes scarcer ...the ability to "effect" the process of technological advancement to jump clear of the downward spiral that EVERYTHING gets caught in...becomes that much harder...)

-and factor in ....finally ...the continued upward curve of hunger and demand...

So we may then say...instead of having ..at most a 100 to 200 year maximum before total collapse...
instead we may be lucky and push that ...not to double ...(due to an always increasing curve upward of demand) ...but say rather half again...
Before total viable consumables are ...well...consumed... done and and gone...and we are truly fcuked...
we have a possible minimum of 150 to a maximum of a possible 300 years before total collapse ...
This is of course depending mainly on consumptive rates...
Our consumptive rate has sped up since knowing there is less...
When it becomes wholesale knowledge to the public anticipate consumptive rates of natural resources planet wide to go through the roof...as nations and peoples fight over resources...plunder and clear-cut their way through the rest of the planet at an even more accelerated rate.

So I am being generous and liberal in my estimate...

a severe estimate before the damage becomes endemic collapse would be under 50 years...

my personal guessing "hope" would be a 100 years ...before things get really bad.
(mainly because I "hope" to be dead before the worst hits )