It's a huge country with a lot of different cultures.  Popular sports vary by region so pretty much everything is represented.  Where I live, basketball and NASCAR are big but a lot of people also play baseball.  Go a few states in either direction and it might be a different picture.  Then, on top of that, ALL of that is on TV or the internet so you can follow something even if it's not in your area.  

Yes but the money generated from media is in a whole other league when it comes to Indian cricket, field hockey was very popular 40/ 50 years and it had much to do with the national teams triumph's around that time.

Ah yeah I totally forgot NASCAR, which I believe I've heard is right up there with American Football in popularity.

I've always liked the regional differences as it's fun to see different sports remaining alive and well, such as the reemergence of Lacrosse. Of course, Florida is mostly just obsessed with American Football (and obviously some NASCAR/NBA), which has lead me to severely disappoint people I've met from farther north when I'm forced to admit that I know next to nothing about Hockey.

It's the same in Australia,  the states of New South Wales and Queensland are rugby league strongholds while the rest of the States and the Northern Territory are Australian rules strongholds. a similar thing happens in the UK where Northern England has a strong rugby league background not found around the rest of the UK and cricket is played in sucessfull leagues in both Scotland and Wales but it is seen as an English pastime shown by the fact you play cricket for England sometimes it is simply the weather conditions that dictate the sports played other places like in the US and Australia colonization and immigration have played a part. 

Since I personally don't follow football I don't even know what the matchfixing scandal was, imho the reasons why football is losing popularity are various: 

-the same football club has won the Serie A for like 5 years in a row now, people start losing interest when the same team wins over and over again;

-various teams went though either bankrupcy or a buyout from other countries (US/China) that lessened the interest in the teams for some people (i.e. Milan F.C. was owned by our sadly famous ex-prime minister Silvio Berlusconi before he sold it to a group of Chinese milionaires);

-our market for players has been rather awful in the past years with great players like Ibrahimovic and Pogba leaving without anyone of the same level to come replacing them. That being said I heard that this year many clubs are buying A LOT of good players (especially Milan) but yet no great talents;

Imho this year we will se a change in the trend but if the italian clubs can't sustain this same activity on the market (or even exceed it) ifootball will start decreasing in popularity again

Yes it's called the Barassi Line. Traditionally rugby league was the most popular sport in New South Wales and Queensland while being niche in the rest of the country. Aussie rules is quite niche in New South Wales and Queensland but is the most popular sport in the rest of the country.

Are you in Aussie rules or rugby league territory?

Aussie rules I live in Tasmania. I was surprised you knew about the barrasi line you must be well informed or someone who likes tolookinto info presented to them.

Yes, I do like to read about sports and Australia is really fascinating when it comes to sports. But unfortunately living in Canada I've never met another AFL fan in my life. I don't get why Tasmania doesn't have an AFL team but Gold Coast does (Sydney I can understand because of how many people are there). I'm a Richmond fan. If we had enough fans on here I would consider starting an AFL thread.

The reasons pretty simple really , Tasmania is a captive market and offering nothing in regards to adding extra games to sell to pay TV since they don't want to go to an uneven number of teams so a relocation is the only way forward unless we became rugby converts overnight then something would happen.

Also vestered intests play a large part , Just like the AFL and the VFL before it benefited from some of the greatest players of all time coming from Tasmania so do today's, Victorian based teams reap considerable benefits  from the Tasmanian supporter base in terms of membership and merchandise sales , that's not taking into account Hawthorn who plays 4 games a season in Launceston they went from near bankrupt to where they stand today and that change of fortune both financially and on field coincides with the Tasmanian deal,  they have well over 10,000 paid up Tasmanian members and according to the club to make the same income they get from a single Tasmanian game they would  need a 70,000 home crowd at the MCG .

Did you follow fellow canadian Mike Pikes career at the Swans and iirc there is AFL Canada check their website  and the national side calledNorthwinds play in an international series.

Uh, no. Absolutely not. NASCAR isn't near top 5 in popularity. I would even suggest it's behind Soccer and Hockey.