Do you plan to support namespaces? This feature of new linux kernels allow build "virtual routers" without "hardware virtualisation" on any hardware.

Network namespaces support would additionally provide the ability of being able to construct two active/backup bond interfaces using only two network interfaces. This is useful in scenarios where 10Gbps switches do not have a high speed backbone and where inter-stack traffic becomes the bottleneck. This would enable one to, for example, run storage replication traffic on one switch via bond1 whilst keeping virtual machine traffic on the other switch via bond0. Either interface could however fail and traffic would subsequently be combined on the remaining port.

Herewith the steps on how to get this done in openvswitch:
# ovs-vsctl add-br br0
# ovs-vsctl add-br br0
# ovs-vsctl add-bond br0 bond0 eth2 veth00 -- set port bond0 bond_mode=active-backup -- set interface veth00 type=patch options:peer=veth01
# ovs-vsctl add-bond br1 bond1 eth3 veth10 -- set port bond1 bond_mode=active-backup -- set interface veth10 type=patch options:peer=veth11
# ovs-vsctl add-port br0 veth11 -- set interface veth11 type=patch options:peer=veth10
# ovs-vsctl add-port br1 veth01 -- set interface veth01 type=patch options:peer=veth00
# ovs-appctl bond/set-active-slave bond0 eth2
# ovs-appctl bond/set-active-slave bond1 eth3

Linux namespaces would probably also provide better isolation than the current Mikrotik VRF implementation although I'm not 100% sure myself. The current VRF implementation in RouterOS utilises separate routing tables but the link local table is always consulted so assigning an IP to another interface would result in the router processing packets when they are destined to that IP, even when the interface routing the traffic is in an isolated VRF routing table.

Namespaces could be used as a base for VRFs in ROSv7, but is not 100% decided yet.