Right now we can only detect light of a certain age. To a certain age. And therefore a certain distance. This is because of the sensitivity of our instruments and the back ground noise level. And the fact that light dissolves with distance.
Light can get so old, that it losses it's direction. The direction loss comes from the density loss. It becomes back ground noise. ORPHAN EM propagation. The source is now black. Only detectable as noise. A slight temperature as the result of continuous fleeting superposition.
How old could light get before it is so thin that it doesn't exist? This cosmos is probably older than that. Much older.
But it's just another guess. If we could see what the present cosmos looks like, we might be shocked. There could be a galactic super nova coming straight at us, only 500 LYs away.
If the MW blew up today, we would not see it or know it till it hit us. 25K years from today.