But the other face of the coin is that you loose leverage to keep them close.
One thing is having to duplicate the infrastructure in the worst case another of loosing the whole region no?
Honestly, to really get into this sort of discussion gets into a number of legal, economic, and socio-political domestic Canadian arenas, which can get perilously OT and borderline appropriate for DT. I have this caveat, that I have a definite bias towards the rest of Canada, and away from any Quebecois independence/sovereignty movements. Part of this is due to my views of history, and part of this is due to family connections to Ontario and Manitoba specifically, as well as the UK and various current and former British colonies and/or Commonwealth nations.
As it is (and this can be a sore subject amongst Canadians) the Canadian gov't makes "equalization payments" to some provinces to "balance out" collected revenues, with a few provinces being net contributors (Alberta, BC, Newfoundland & Labrador, Sasketchwan) and others being net receivers (PEI, New Brunswick, Nova Scotia, Manitoba, Quebec, Ontario). I believe the equalization payments having been occurring since confederation in one form or another, but the system was formalized in 1957. While Quebec, by virtue of it's large population (2nd largest province population in Canada), had the 2nd lowest per capita equalization payment for 2016-2017 at CAN$1,206 per person or CAN$10.03 bil. in total, that $10.03 bil. still exceeded the amount of equalization payments received by all the other provinces by CAN$2.18 bil. In effect, the rest of Canada has already, to one degree or another, been subsidizing Quebec and this has been going on for at least the past 40 years. It is also worth noting that ON, the other province with a large population which also receives equalization payments, received a total of only CAN$2.304 bil. or CAN$166 per capita in the 2016-2017 fiscal year, or only ~23% of the amount Quebec received.
Due to this, as well as Canadian gov't efforts to support Quebec-based companies like Bombardier, there seems to be sentiments that Canada is already doing quite a bit to subsidize Quebec and yet there remain elements within the French-speaking population of Quebec that seem to think it would be better if the province (majority are fluent in French/of French descent) was separate from the rest of the predominantly English-speaking and originally British settled Canada. As a side note, it seems that several of the First Nations tribes located within Quebec are not in favour of separating from the rest of Canada.
Historically, the province of Quebec had basically been the Colony of New France, which was captured by the British during the Seven Years War and France ceded the territory to Britain with the Treaty of Paris (1763). For me, that causes some issues since those who seem most interested in sovereignty are interested along the lines of a quasi ethno-nationality rationale, when the area had not experienced self-rule until it was granted so by the British gov't after joining the Canadian Confederation about a century after France yielded territory. Also, in addition to not having previously had self-rule prior to being conquerored by the British in 1759, the French settlers and their descendants were themselves just that, settlers and not native to the area, with Quebec City having been founded circa ~1608. With most of the rest of the world where there are or have been independence movements, especially within overall minority populations with areas of local majority, the populations have been within those specific areas for centuries if not thousands of years and have historically had a degree of self-rule.
With all that in mind, a decision to have more funding flow from federal coffers into a would-be breakaway province that would likely have problems functioning independently, and that would also likely have a different political and diplomatic outlook at odds with the remaining provinces of Canada, would seem unwise IMO.
