Well, I think using current affairs as the basis for the new timeline is the wrong way to go, if for no other reason than the entire Islamic world (whatever that is) put together couldn't hurt the US.
figure all of north africa, the middle east, pakistan, and the break away states of Russia <chechnya, kazekstan, turkmenistan> Malaysia and co. added all together i would imaging the islamic nations could form a powerful alliance, especially if you assume some industrialisation in a few key nations such as Egypt and Malaysia.
Though I could understand the writers being a bit leery of casting the Islamists as the bad guys but its not an entirely impossible future.
another option is this.
USA is the bad guy..a fundamentalist christian leader is elected and assumes the role of charismatic dictator <alah revolution 2020> and starts trowing its weight around in the Americas. Canada resists while Mexico joins the US. Wars wage from the arctic to the antartic as Fascist USA and its allies roll over one country after another...Texas and Alaska withdraw from the union and are invaded, intense fighting near dallas, Alaskans light up the pipeline to slow down US armor.
Canada is swept under advancing US armor but manage to hold Ontario during harsh fighting in the winter of 2020. 200,000 die in the siege of Ontario but they hold. Quebecoix<sp?> government betrays the canadians and joins the US side but falls into a state of civil war before it can bring its army to bear against the rest of canada. loyalists and rebels grind the city to dust in harsh city block to city block warfare but loyalist win after US troops withdrawing from Ontario intervene.
Mexico crushes Central america with its combination of man power and US made equipment, the world protests the massacre of managua where mexican units execute 100,000 civilians. Mexican 901st Inf{mech} rolls into south america but meets stiff resistance from Colombian units holding the andes mountain passes. The front grinds into a war of attrition in the jungles and highlands with Mexico slowly gaining the upper hand.
US marines land in Brazil and Argentina. Chile joins the US alliance and invades colombia from the south and Bolivia. Chile/US forces take Bogota but suffer huge losses due to the Bolivian militarys use of newly supplied, state of the art european made weapons. War slowly grinds into a jungle war in the Amazon basin.
Meanwhile In Europe the Italian, Spanish, Russian, and French governments all join the US led alliance. this causes the most problems in france and Russia where the move angeres both their nieghbors and their sizable Islamic populations. After some protests and riots French military units ruthlessly crush protestors drawing cries of outrage from its north african nieghbors and the more moderate nations of Europe. when France begins shipping its muslim citizens to internment camps war is declared by the North African alliance.
French fighters and naval assets are hard pressed to hold back the combined forces of Egypt, Libya, and Algeria who make tremendous use of newly supplied Chi-com fighters and lift assets. 498th swords of Jibril <Egypt> land on Sardinia while units with the Libyan naval infantry occupy southern Italy. Italian counter attack leads to the day of the bloody sea as thousands of retreating NAA troops are slaughtered on the beach south of Napals<sp?>.
Russian Troops enter the mediterranean arena when they move the southern fleets from the black sea. during the move rounds are exchanged between Russian ships and Turkish units. Turkey declares War on the US alliance and is answered in turn.
a few months later Russian armor crosses thru Georgia and into Turkey. this cause a chain reaction as war is declared by Iraq, Iran, Syria, Jordan, Pakistan, and Saudi Arabia.
The UK closes its borders and attempts to blockade itself from the rest of europe.
Indian Invades Pakistan. no one is sure why but years of bad blood are finally acted upon.
German units on maneuvers near the French border stumble across and are attacked by French units. before the German government is aware of the situation french forces have penitrated 50 kilometers into Germany and the French government has declared war. Germany declares war in turn and counter attacks, french units are decimated as german units push into France. German units crush the already strained french units and moves into the outskirts of Paris.
in Spring 2028 US and Mexican forces Land in France and move to engage the German army while Russian forces blitz thru Poland, Russian troops with czech allies are engaging german forces within 50 kilometers of berlin within two months. In the fall Chinese troops move into Siberia and invade the Alaskan islands. Russian eastern units move to engage but are overwhelmed by the Chi-com forces.
Combined Syrian, Egyptian, Iraqi, Iranian, and Jordanian forces Invade Israel, Israeli forces fight fiercely for every inch of ground but are pushed back. Jerusalem falls. Tel Aviv holds only due to the quick landing of Russian spetznaz and US airborn units.
April 5 2028 21:00am Russian commander Vasily Proschev orders the launch of Nuclear missles against Chinese troop concentrations. China answeres in kind. within the next week nearly every missle in every arsenal is launched.
Sorry for the length of the post and the horrid spelling and grammar. just shareing a few ideas