You won't be able to remove the single point of failure without a backup connection. With two WAN lines, here's how I'd do it:
Two routers, one WAN link on each. If one of the WAN lines are considered backup, bump up the ospf interface cost of that one.
Assuming a LAN of 192.168.1.0/24, give router1 192.168.1.2/24 and router2 192.168.1.3/24, define a vrrp interface on both, like:
/interface vrrp add interface=ether1 name=ether1.vip authentication=simple password=foobar arp=enabled preemption-mode=yes priority=5 vrid=1
/ip address add interface=ether1.vip address=192.168.1.1/32 disabled=no
Do exactly the same on the other router, but change the priority.
Connect both interfaces to the LAN, and make sure your default gateway on your clients is 192.168.1.1.
Voila, redundant routers and redundant WAN. This assumes that a default route is given via OSPF on both WAN links.
If you have only one WAN link, attach your WAN line to a switch and attach both routers to that switch. Buy a quality switch, or your clients will kill you if (when!) it crashes.