Add them both into the English Premier League, with access to the same revenue streams etc, and it wouldn’t take long before they became a force.
The value of each club would sky rocket and based on fan base, history and global appeal, would attract interest from some of the richest investers on the planet.
American investment is huge right now, so let’s take the Irish American side of things..
Celtic have a huge fan base in the states, now if the club were suddenly shopping in the same market as half of the Premier League, the level of interest would only grow and commercial opportunities would explode.
The politics, religion and the like are one side of the story, but in terms of stature, how many English clubs have a real legacy status that’s higher right now?
Liverpool, Man Utd, Arsenal perhaps?
Ask yourself this question.. If Celtic and Rangers played in England, on a level playing field with the same money from TV, would they have a realistic chance of competing with the likes of Spurs, Villa and Newcastle?
It would take time of course but in the long run the answer has to be yes.